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RESERVED 


Soil  Surveys 
Stockton  #67 


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of  Cai(((yr^  Los  Angeles 


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Ill  be  tor  the  use  of  eacli  Senator  from  the  !?tate,^wo  tliousand  copies'for  the  use  of 
•h  Representative  for  the  congressional  district  or  districts  in  -w-hich  the  survey 
nade,  and  one  thousand  copies  for  the  use  of  the  Department  of  A^culture. 
Approved,  March  14,  1904. 

[On  July  1, 1901,  the  Division  of  Soils  was  reorganized  as  the  Bureau  of  Soils.] 


Geology-Geopnysics  Library 
4697  Geology 
University  of  California 
Los  Angeles,  CA  90024 


[PtrBLio  Resolution — No.  9.^ 

T  RESOLUTION  Amending  public  resolution  numbered  eight,  Fifty-sixth  Congress,  second  ses- 
,  approved  February  twenty-third,  nineteen  hundred  and  one,  "  providing  for  the  printing  annually 
16  report  on  field  operations  of  the  Division  of  Soils,  Department  of  Agriculture." 

solved  by  the  Saiate  and  House  of  Representatives  of  the  United  States  of  Ameiica  in 
ress  assembled,  That  public  resolution  numbered  eight,  Fifty-sixth  Congress, 
'-J  session,  approved  February  twenty-ihird,  nineteen  hundred  and  one,  be 
ided  by  striking  out  all  after  the  resolving  clause  and  inserting  in  lieu  thereof 
tollovving: 

lat  there  shall  be  printed  ten  thousand  five  hundred  copies  of  the  report  on  field 
ations  of  the  Di-vision  of  Soils,  Department  of  Agriculture,  of  which  one  thousand 
hundred  copies  shall  be  for  the  use  of  the  Senate,  three  thousand  copies  for  the 
of  the  House  of  Representatives,  and  six  thousand  copies  for  the  use  of  the  De- 
ment of  Agriculture:  Provided,  That  in  addition  to  the  number  of  copies  above 
,  ided  for  there  shall  be  printed,  as  soon  as  the  manuscript  can  be  prepared,  with 
ecessary  maps  and  illustrations  to  accompany  it,  a  report  on  each  area  sm-veyed, 
0-  :.  form  of  advance  sheets,  bound  in  paper  covers,  of  which  live  hundred  copies 
snail  be  for  the  use  of  each  Senator  from  the  State,  two  thousand  copies  for  the  use  of 
each  Representative  for  the  congressional  district  or  districts  in  which  the  survey 
is  made,  and  one  thousand  copies  for  the  use  of  the  Department  of  Agricult;ire. 
Approved,  March  14,  1904. 

[On  July  1, 1901,  the  Division  of  Soils  was  reorganized  as  the  Bureau  of  Soils.] 


Geology-Geophysics  Library 
4697  Geology 
University  of  California 
Los  Angeles,  CA  90024 


xCE. 


RECONNOISSANCE 
AREAS 


Areas  suiVeyed  in  CaliXomia. 


U.  S.  DEPARTMENT   OF  AGRICULTURE, 

BUREAU  OF  SOILS— MILTON  WHITNEY,  Chief. 


SOIL  SURVEY  OF  THE  STOCKTON  AREA, 
CALIFORNIA. 


MACY  H.  LAPHAM  and  W.  W.  MACKIE. 


[Advance  Sheets— Field  Operations  of  tlie  Burean  of  Soils,  1905.] 


WASHINGTON: 

GOVERNMENT    PRINTING    OFFICE. 

1906. 


LETTER  OF  TRANSMITTAL. 


U.  S.  Department  of  Agriculture, 

Bureau  of  Soils, 
Washington,  D.  C,  May  2Jf,  19G6. 

Sir  :  During  the  season  of  1905  a  soil  survey  was  made  of  an  area 
around  Stockton,  Cal.  Requests  for  this  work  showed  a  variety  of 
special  interests  which  would  be  served.  The  following  request, 
transmitted  by  the  Hon.  J.  C.  Needham  and  indorsed  by  him,  sets 
forth  the  conditions  in  the  region  : 

The  peat  soils,  the  adobe  soils,  and  other  characteristic  soils  around  Stockton 
have  never  been  studied  in  a  scientific  manner.  The  great  Tokay  belt  of  Cali- 
fornia is  supposed  to  lie  just  north  of  Stockton.  The  limits  of  this  area  have 
never  been  determined.  Vineyardists  are  experimenting  every  year,  setting  out 
Tokays  and  losing  their  investments  from  lack  of  knowledge  of  soil  and  climatic 
conditions,  the  very  conditions  that  a  soil  survey  would  establish.  I  know  of 
no  one  thing  that  would  do  more  to  build  up  this  part  of  California  than  a  soil 
survey.  Not  only  would  it  help  our  own  people,  but  it  would  attract  to  central 
California  ruany  people  because  of  the  facts  that  would  be  established. 

The  making  of  this  survey  was  also  advocated  by  Senator  George  C. 
Perkins,  and  in  compliance  with  these  requests  a  survey  of  the  Stock- 
ton area  was  made.  The  work  in  this  area  should  form  a  basis  for 
the  further  extension  of  the  survey  of  the  soils  of  this  region,  and  it 
would  seem  advisable  to  continue  the  survey  to  cover  the  greater  part 
of  the  Tokay  grape  region. 

I  transmit  herewith  the  map  and  report  on  the  Stockton  area,  Cali- 
fornia, for  publication  as  advance  sheets  of  the  Field  Operations  of 
the  Bureau  of  Soils  for  1905,  as  authorized  by  law. 
Respectfully, 

Milton  Whitney, 

Chief  of  Bureau. 
Hon.  James  AA^ilson, 

Secretary  of  A(/riculture. 

2 


Librar] 

S  ■ 


CONTENTS. 


Page. 

Soil  Survey  of  the  Stockton  Area,  California.    By  Macy  H.  Lapham 

and  W.  W.  Mackie -  -  -  5 

Location  and  boundaries  of  the  area 5 

History  of  settlement  and  agi'iciiltural  development 6 

Climate - 7 

Physiography  and  geology 9 

Soils ---- --.-  10 

San  Joaqnin  loam 11 

Stockton  silt  loam  . 12 

Fresno  sandy  loam 13 

Fresno  fine  sandy  loam ..- -. 15 

Fresno  sand 16 

Fresno  fine  sand - 17 

San  Joaquin  sandy  loam ^ 18 

Stockton  loam 18 

Stockton  loam  adobe 20 

Stockton  clay  adobe 21 

Stockton  clay  loam  adobe 23 

Sacramento  clay  loam 23 

Peat - - - 25 

Special  soil  problems - -.-  27 

Reclamation  of  swamp  lands 28 

Water  supply  for  irrigation 30 

Underground  and  seepage  waters 31 

Alkali  in  soils -  32 

Agriciiltural  methods 34 

Agricultural  conditions 36 


ILLUSTRATIONS. 


PLATES. 

Pago. 

Plate    I.  Alkali  map.  Stockton  sheet,  California 32 

II.  Black  alkali  map,  Stockton  sheet,  California 32 

TEXT  figure. 
Fig.  1.  Sketch  map  showing  location  of  the  Stockton  area,  California 5 

MAP. 

Soil  map,  Stockton  sheet,  California. 


SOIL  SURVKY  OF  THE  STOCKTON  ARI^A,  (WLIFORNIA. 

By  MACY  H.  LAPHAM  and  W.  W.  MACKIE. 


I.OCATIOX    AND   BOITNDARIES   OK   THE   AKKA. 

The  Stocklon  area  lies  in  the  northern  or  h)wer  part  of  the  San 
Joacjiiin  Valley,  entirely  witliin  the  count}'  of  San  Joaquin,  and  ne'ar 
the  geographical  center  of  the  State  of  California,  It  is  nearly  rec- 
tangular in  shape  and  has  an  extent  of  333,248  acres,  or  about  521 


Fig.  1. — Sketch  map  showinp  location  of  the  Stockton  arcfi,  ralifoniia. 

square  miles.    The  city  of  Stockton  is  situated  near  the  center  of  the 
area. 

The  base  map  used  in  the  soil  survey  was  made  b}^  the  party  in  the 
field  as  the  work  progressed,  no  accurate  published  map  being 
available. 


6  FIELD    OPERATIONS    OF    THE    BUREAU    OE    SOILS,   1905. 

HISTORY   OF   SETTLEMENT   AND   AGRICULTURAL   DEVELOPMENT.' 

In  the  history  of  the  discovery  and  early  exploration  of  California 
the  Jesuit  priests  and  missionaries  with  their  followers  played  im- 
portant and  romantic  roles.  The  scene  of  their  struggles  and  sac- 
rifices was,  however,  mainly  confined  to  the  coastal  region.  While 
the  San  Joaquin  River  owes  its  discovery  in  1783  to  the  Jesuit  mis- 
sionary. Father  Crispi,  the  exploration  and  the  settlement  of  the  dis- 
trict covered  by  this  report  fell  to  Americans  and  French  Canadians 
at  a  later  date. 

The  first  of  these  to  visit  the  San  Joaquin  Vallej^  were  hunters  and 
trappers,  some  of  them  in  the  service  of  the  historic  Hudson  Bay 
Company.  At  that  time  wild  game,  consisting  of  bear,  deer,  elk, 
and  antelope,  wild  horses  (escaped  from  the  early  Spanish  adventur- 
ers and  mission  padres  during  their  pilgrimages  along  the  coast) ,  and 
many  smaller  fur-bearing  animals  were  abundant.  These  nomadic 
trappers  explored  the  network  of  streams  and  held  undisputed  sway 
over  the  valley  for  a  period  of  about  twenty  years  prior  to  1844. 

In  1843  a  tract  of  land  embracing  over  48,000  acres,  near  the  center 
of  the  area  surveyed,  and  including  the  site  of  the  j)resent  city  of 
Stockton,  was  obtained  from  the  Mexican  Government,  under  the 
title  of  the  Campo  cle  los  Franceses  grant,  by  Capt.  C.  M.  Weber,  of 
San  Jose. 

This  was  followed  by  the  arrival  of  a  few  early  settlers  and  the 
founding  of  a  few  small  colonies,  the  earliest  farming  being  carried 
on  along  the  Calaveras  River.  Early  but  temporary  settlements  were 
also  made  b}^  the  Mormons  at  French  Camp  and  upon  the  banks  of 
Mormon  Slough.  The  city  of  Stockton  was  founded  by  Captain 
Weber  in  1847. 

With  the  rush  of  gold  seekers  to  California  immediately  after  the 
discovery  of  this  metal  in  1848,  Stockton  became  one  of  the  objective 
points  and  an  important  outfitting  station  for  the  mines.  The  popu- 
lation, although  of  a  somewhat  unstable  character,  rapidly  increased, 
representing  nearly  all  States  and  nationalities  of  the  world.  The 
most  of  these  came  by  sailing  vessels  by  way  of  the  Horn,  and  four  d 
their  way  to  the  San  Joaquin  River. 

Early  efforts  in  agriculture  were  for  the  most  part  confined  to  stock 
raising.  With  the  sudden  increase  in  population,  prices  of  farm 
l^roducts  gi-eatly  advanced.  Vegetables,  hay,  grain,  and  other  staple 
crops  were  in  demand.  Some  of  those  who  came  in  quest  of  gold 
found  their  wealth  only  when,  as  a  last  resort,  they  turned  iheir  atten- 
tion toward  producing  supplies  for  the  mines.  The  growing  of 
wheat  in  large  tracts,  however,  became  the  main  agricultural  indus- 
tr3\  Later  barley  came  into  favor,  and  the  ]:)roduction  of  these  two 
grains  is  still  of  leading  importance.     The  use  of  farm  machinery 


SOIL    SURVEY    OF   THE    STOCKTON    AREA,    CALIFORNIA.  7 

consistent  with  the  farming  of  extensive  tracts  became  an  early  oiit- 
growtli  of  this  practice.  Sailing  vessels  were  partly  supplanted  by 
steam  river  packets.  Then  came  the  railroads,  and  Stockton  became 
an  important  manufacturing  center  and  grain  and  hay  shipping  point. 

With  more  recent  iimnigration  the  population  has  taken  on  an  even 
more  cosmojjolitan  character,  and  this  has  resulted  in  i'njjroved  agri- 
cultural practices.  Reduction  of  profits  in  grain  ranching,  owing  to 
declining  yields,  the  occurrence  of  dry  years,  and  to  unfavorable 
prices,  has  opened  the  way  for  the  introduction  of  irrigation  and  a 
system  of  diversified  farming,  including  especially  the  growing  of 
vines,  fruits,  alfalfa,  and  the  production  of  stock  and  dairy  products. 

Within  the  last  few  years  the  reclamation  and  utilization  of  the 
rich  peat  lands  of  the  western  part  of  the  area  have  proceeded  rap- 
idly, with  the  consequent  improvement  in  shipping  facilities  by  water 
and  the  addition  of  the  special  crops  of  this  section  to  the  staple 
agricultural  products  of  the  earlier  developed  parts  to  the  east. 

CLIMATE. 

The  climate  of  the  Stockton  area  is  characteristic  of  the  lower  San 
Joaquin  and  Sacramento  valleys.  It  is  marked  by  the  occurrence 
of  two  seasons,  a  wet  and  a  dry,  contrasting  considerably  in  tempera- 
ture, and  widely  in  precipitation,  humidity,  wind  movement,  and  the 
relative  number  of  clear  days. 

The  normal  annual  temperature  at  Stockton  is  about  00°  F.  Nor- 
mal monthly  temperatures  vary  from  a  maximum  of  about  72.5°  F. 
for  the  months  of  July  and  August  to  about  46.5°  F.  for  the  month 
of  January.  In  the  summer  months  high  temperatures  are .  fre- 
quently reached  during  the  day,  but  the  nights  are  usually  cool 
and  pleasant.  During  the  winter  or  rainy  season  periods  of  clear 
weather,  often  accompanied  by  frost,  are  of  frequent  occurrence. 
Killing  frosts  may  occur  as  early  as  November  and  continue  into 
the  month  of  April,  but  are  usually  confined  to  the  winter  months 
and  rarely  are  so  severe  as  to  interfere  with  farming  operations. 

The  average  annual  precipitation  amounts  to  about  15.5  inches, 
taking  place  almost  entirely  during  the  period  from  November  to 
April,  inclusive.  The  rains  commonly  occur  as  gentle,  steady  showers, 
or  in  rainy  periods  continuing  from  onef  to  three  days,  interspersed 
with  periods  of  clear  or  foggy  weather.  The  occurrence  of  snow, 
violent  storms,  and  thunderstorms  is  very  rare. 

A  condition  of  low  relative  humidity,  accompanied  by  cloudless 
skies,  generally  occurs  during  the  summer  season,  but  is  less  marked 
than  in  the  upper  and  drier  portions  of  the  San  Joaquin  Valley.  It, 
however,  greatly  lessens  the  sensible  temperature  of  the  hot  summer 
da3^s.  Throughout  the  winter  season  the  atmosphere  is  frequently 
laden   with   moisture   during   intervals   between   cloudy    and   rainy 


8 


FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,    1905. 


periods,  and  dense  fogs  are  of  frequent  occurrence.  During  the 
night  and  early  morning  the  fogs  are  generally  dense,  but  they 
frequently  disappear  or  lift  during  the  day,  sometimes  continuing, 
however,  as  "  high  fog  "  for  unbroken  periods  of  several  days,  and 
even  occasionally  for  weeks  at  a  time.  These  winter  fogs  form  a 
prominent  local  climatic  feature  of  the  great  interior  valley  of  Cali- 
fornia, and  although  obscuring  the  sun  for  long  intervals,  are  unac- 
comj)anied  by  rain,  are  distinguished  from  ordinary  cloud,  and  are 
considered  in  the  official  records  as  fair  Aveather. 

During  the  winter  the  winds  are  variable  and  light  in  character. 
During  the  summer  season  wind  movement  is  dominated  by  the  sea 
breezes,  entering  the  valley  by  way  of  the  Straits  of  Karquines,  of 
moderate  briskness,  and  greatly  tempering  the  heat  of  the  inte];'ior. 

The  climate  is,  as  a  whole,  healthful  and  well  adapted  to  the  pro- 
duction of  general  farm  and  truck  crops.  A  lai'ge  proportion  of  the 
winter  rains  is  retained  by  the  soils  to  be  used  in  plant  production, 
while  during  the  harvest  season  but  little  or  no  hindrance  is  expe- 
rienced in  farming  operations  because  of  unfavorable  weather.  The 
growing  of  the  more  tender  fruits  is  rendered  somewhat  hazardous, 
owing  to  the  occurrence  of  late  warm  winter  periods  sometimes  fol- 
lowed by  frosts,  but  hardier  fruits  and  ordinary  farm  crops  are  un- 
harmed by  frost,  while  the  hardier  vegetables  and  truck  crops,  such 
as  onions,  cabbages,  etc.,  are  produced  the  year  round. 

The  normal  monthly  and  annual  temj^erature  and  precipitation, 
as  compiled  from  official  data  of  the  Weather  Bureau,  reported  for 
the  stations  at  Stockton,  Lodi,  and  Tracy,  the  latter  two  located  just 
outside  the  northern  and  the  southern  boundaries  of  the  area,  respec- 
tively, are  shown  in  the  following  table : 

Nornidl  DiontliJy  and  annual  temperature  and  precipitation. 


Stockton. 


Month. 


Temper-   Precipi- 
ature.       tation. 


Tracy. 


Lodi. 


Temper-  Precipi- 
ature.       tation. 


January . . . 
February . . 

March . 

April 

May 

June 

July 

August 

September 
October  . . . 
November 
December . 

Year. 


F. 

46.9 

50.5 

54.8 

60.9 

69.1 

75.9 

79.9 

77.5 

73.0 

63.5 

54.2 

49.6 


In. 

1.64 

1.16 

1.53 

.95 

..55 

.18 

.01 

.01 

.19 

.60 

1.15 

2.16 


F. 

46.2 

50.1 

54.7 

58.3 

63.4 

69.1 

73.7 

73.0 

69.7 

62.3 

53.6 

47.3 


3.71 

2.26 

3.02 

1.27 

1.36 

.19 

.00 

.05 

.46 

1.42 

2.49 

3.56 


15.41 


62.9 


10.13 


60.1 


19.79 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA.  9 

PHYSIOGRAPHY    AND    GEOLOGY. 

In  general,  the  area  surve3'ed  is  without  marked  topographic 
variety,  the  most  noteworthy  feature  consisting  of  the  advanced 
drainage  sj'stem.  The  elevation  ranges  from  that  only  slightly 
above  sea  level  and  below  mean  high-tide  level  upon  the  western  or 
river-delta  part  of  the  area  to  slightly  more  than  100  feet  above  sea 
level  at  the  northeastern  extremity.  The  slopes  are  in  general  scarcely 
noticeable  and  the  area  is  devoid  of  rock  outcrop,  bluff,  or  terrace 
lines.  Tree  growth  usually  occurs  only  in  the  vicinity  of  the  streams 
as  groves,  or  as  scattered  individuals  upon  the  lower  valley  plain. 
Drainage  is  effected  by  the  San  Joaquin  River,  with  its  tributaries, 
the  Calaveras  River  and  ]\Iormon  Slough,  passing  across  the  eastern 
and  central  parts  of  the  area,  while  a  multitude  of  meandering 
branches  of  the  main  river,  with  blind  and  open  tidal  sloughs,  trav- 
erse the  western  half. 

Along  the  northern  i)art  of  the  eastern  half  of  the  sheet,  and  lying 
just  east  from  the  towns  of  Linden  and  Peters,  the  western  edges  of 
the  lower  foothills  of  the  Sierra  Nevada  Mountains  project  into  the 
valley  plain  and  are  included  within  the  boundaries  of  the  area. 
These  first  jDrominent  foothill  slopes  consist  of  treeless  plains  of  quite 
marked  incline  or  of  the  lower,  rounded,  or  gently  undulating  hills 
and  ridges,  covering  only  1  or  2  square  miles,  and  forming  the  only 
prominent  features  of  this  character  in  the  entire  area. 

About  one-half  of  the  area  surveyed  consists  of  the  valle}"  plain 
proper,  at  one  time  covered  by  the  waters  of  an  ancient  Pleisto- 
cene lake  or  bay.  The  central  part  is  traversed  in  a  general  south- 
westerly direction  by  the  Calaveras  River  and  Mormon  Slough, 
the  waters  from  both  of  which  enter  the  San  Joaquin  a  little  below 
Stockton.  Mormon  Slough,  sometimes  called  Mormon  Channel,  is 
itself  a  branch  of  the  Calaveras  River,  which  it  leaves  a  short  dis- 
tance outside  the  northwestern  extremity  of  the  area,  and  now  carries 
nearly  all  the  water  which  at  one  time  found  its  way  through  the 
Calaveras  proper.  Formerlj^  but  an  imperfect  channel  carrying 
water  only  during  flood  periods,  it  owes  its  origin  as  the  main  chan- 
nel to  artificial  cuts  made  for  the  purpose  of  irrigation,  which,  in- 
creased by  the  erosive  action  of  flood  waters,  rendered  the  flow  peren- 
nial and  captured  the  entire  floAV  of  the  Calaveras  at  the  point 
of  diversion,  except  during  flood  periods.  The  bed  of  the  lower 
course  of  ^lormon  Slough  is  filled  to  the  depth  of  many  feet  by 
detritus  derived  from  waste  of  the  mountains,  which  is  frequently 
carried  by  winter  and  spring  floods  into  the  still  waters  of  Stockton 
Channel,  forming  bars  and  impeding  navigation  or  entirely  blocking 
the  harbor  until  removed.  A  movement  is  now  on  foot  to  connect 
the  lower  courses  of  Mormon  Slough  and  the  Calaveras  River,  thus 
13.517— OC  M 2 


10  FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,    1905. 

deflecting  the  bulk  of  the  flood  water  into  the  Calaveras  and  deposit- 
ing the  stream-borne  detritus  in  the  San  Joaquin  Eiver,  where  current 
and  tide  may  assist  in  removing  it. 

Both  the  Calaveras  River  and  Mormon  Slough,  except  near  their 
mouths,  are  narrow  and  deep.  Flood  waters  of  these  two  streams-, 
aided  by  those  from  numerous  minor  intermittent  streams,  have  in 
many  places  deposited  extensive  bodies  of  recent  alluvial  material 
over  the  valley  floor.  Lying  to  the  south  and  eastward  from  Lathrop 
the  outlying  extremities  of  extensive  deposits  of  fine  and  coarse  sands 
of  nearly  level  or  gently  undulating  surface,  locally  known  as  the 
"  sand  plains,"  are  encountered. 

The  San  Joaquin  River  delta,  a  part  of  which  is  included  in  the 
western  half  of  the  Stockton  area,  consists  of  a  vast  tract  of  level 
swamp  or  "  tule  "  lands,  lying  beloM^  the  high-tide  level  of  the  adja- 
cent streams.  Numerous  interlacing  streams  and  sloughs  divide  the 
lands  into  tracts  or  "  islands."  This  natural  division  is  augmented 
by  canals  and  cuts  constructed  in  the  progress  of  reclamation  and 
navigation  interests.  Two  prominent  branches  of  the  San  Joaquin 
River,  viz.  Old  River  and  Middle  River,  which,  with  the  San 
Joaquin  j)roper  and  many  smaller  sloughs,  are  navigable  to  river 
boats  throughout  the  greater  parts  of  their  courses  within  the  area 
surveyed,  traverse  the  delta  lands  of  the  Stockton  area.  The  soil 
consists  of  a  light,  loose  Peat  formed  of  river  sediments  mingled  with 
accumulations  of  organic  matter,  the  remains  of  partially  decom- 
posed masses  of  roots,  stems,  and  fibers  of  aquatic  plants.  This  soil, 
when  drained  and  protected  from  tide  and  flood  waters  by  artificial 
means,  proves  extremely  productive.  These  finer  river  silts  and  sedi- 
ments are  continually  deposited  by  flood  waters  upon  the  lands  when 
not  protected  by  levees,  which  with  the  growth  and  decomposition 
of  vegetable  matter  effects  a  gradual  extension  of  the  delta  toward 
the  sea. 

The  materials  entering  into  the  various  soils  of  the  lower  foothills, 
valley  plain,  and  river  delta  are  derived  from  the  granitic,  volcanic, 
and  other  altered  rocks  of  the  Sierra  Nevada  Mountains. 

SOILS. 

The  soils  of  the  Stockton  area  are  mainly  of  alluvial  or  lacustrine 
origin,  being  deposited  by  subsidence  from  the  waters  of  modem  or 
ancient  streams,  lakes,  or  inland  seas,  or  formed  by  the  growth  and 
partial  decomposition  of  masses  of  aquatic  vegetation  mixed  with 
stream  or  tide  borne  sediments.  Naturally  the  degraded  particles  of 
a  variety  of  rocks  enter  into  the  composition- of  these  complex  depos- 
its. Only  along  the  northeastern  margin  of  the  area  surveyed  do 
deposits  of  less  complexity  occur,  as  colluvial  wash  material  dis- 
tributed by  heavy  rains  and  streams  and  derived  directly  from  the 
residual  materials  of  the  adjacent  foothills. 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA. 


11 


The  houiularics  marking  the  various  soil  types  are  frequently  indis- 
liiicf,  related  types  passing  into  each  other  by  imperceptible  degrees. 
In  the  accompanying  mai)s  such  areas  are  necessarily  separated  by 
lines  somewhat  arbitrarily  drawn.  Nearly  all  the  soils  are  remarka- 
bly productive  and  give  large  yields  wherever  proper  cultural  meth- 
ods are  followed. 

The  extent  of  the  several  types  is  given  in  the  following  table: 

ArruN  of  different  soiLs. 


Soils. 

Acres. 

Per  cent. 

SoiLs. 

Acres. 

Per  cent. 

Peat 

107,584 
53,312 
41,088 
40,832 
23,176 
16,512 
10,304 
9,536 

32.3 

15.9 

12.4 

12.8 

7.9 

4.9 

3.1 

2.9 

Fresno  fine  sand     

8,128 
5,ft52 
5,824 
5;  440 
2,560 

2.4 

Stockton  day  loam  adobe  .. 

SaiTamento  clay  loaui 

Stockton  clay  adobe 

Fresno  sandy  loam 

San  Joaquin  sandy  loam 

Ran  -Tnnqiiin  loam 

1.8 
1.7 
1.6 

Stockton  loam.. 

Stockton  loam  adobo 

Total 

.8 

Stockton  silt  loam 

333,248 

Fre.'^no  fine  sandy  loam 

Frasn  jsand 

SAN    .lOAQUIN    LOAM. 

The  surface  of  the  San  Joaquin  loam  consists  of  a  bright  to  dark 
red  plastic  loam  of  fine,  somewhat  silty  texture  and  firm,  compact 
structure,  with  a  depth  ranging  from  a  few  inches  to  3  or  more  feet. 
It  frequently  carries  gravel  throughout  the  soil  section,  though  not 
uniformly  distributed.  "\Alien  in  projDer  moisture  condition  it  breaks 
upon  cultivation  into  a  loose  loam,  but  becomes  very  sticky  wdien  wet, 
with  a  tendency  to  puddle  and  bake  upon  exposure.  In  the  lower 
part  of  the  section  the  soil  suddenly  becomes  heavier,  taking  on  the 
properties  of  a  heav}^  adobe.  This  material  extends  for  only  a  few 
inches,  passing  into  an  impervious  hardpan  of  red  color,  and  generally 
of  fine  texture  and  firm,  dense  structure.  This  hardpan  stratum  will 
be  discussed  further  in  a  succeeding  part  of  this  report. 

The  San  Joaquin  loam,  while  covering  extensive  tracts  of  the  foot- 
hills of  the  Sierra  Nevada  Mountains,  occurs  in  the  area  surveyed  only 
in  a  few  relatively  small  and  unimportant  bodies,  lying  along  and 
adjacent  to  its  northeastern  boundary.  It  forms  the  rolling  uplands 
of  the  lower  or  first  foothill  slopes,  and  extends  to  the  margins  of  the 
nearly  level  valley  plain.  These  slopes  and  rolling  hills  are  treeless 
and  devoid  of  rock  outcrop  or  similar  features,  save  for  the  occasional 
appearance  of  the  underlying  hardpan. 

Natural  drainage  is  favored  by  the  elevated  position  and  well- 
defined  slopes  of  these  soil  bodies.  '\Miile  the  surface  run-off  is  thus 
generally  free,  percolation  is  greatly  retarded  and  in  many  cases  pre- 
vented by  the  underlying  hardpan,  so  that  the  surface  waters  fre- 
quently collect  and  remain  in  local  drainage  depressions  until  dis- 
pelled by  evaporation.     The  soil,  following  wet  seasons,  is  conse- 


12 


FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS^    1905. 


qiiently  marked  by  wet  and  boggy  spots  and  is  often  cultivated  with 
diiRciilty.  On  the  other  hand,  it  frequently  becomes  compact,  hard, 
and  impracticable  of  cultivation  before  the  advent  of  the  winter 
rains.  These  conditions  greatl}^  limit  the  variety  of  crops  grown  and 
the  period  of  successful  cultivation  of  these  lands. 

The  San  Joaquin  loam  is  derived  from  valley  sediments  of  early 
Pleistocene  age  and  from  the  weathered  product  of  the  complex  rocks, 
generally  of  metamorphosed  or  altered  character,  of  the  Sierra 
Nevada  foothills,  the  latter  material  being  gradually  transferred  and 
spread  about  the  valley  margins  through  washing  by  torrential  rains 
and  streams.  Some  of  these  soil  bodies  are  obviously  modified  by 
an  admixture  of  recent  alluvium.  The  soil  and  subsoil  are  free  from 
alkali  salts  in  injurious  amounts. 

In  other  parts  of  California  soils  of  essentially  the  same  characteris- 
tics as  the  San  Joaquin  loam  have  been  successfully  devoted  to  fruit 
culture,  but  owing  to  the  shallowness  in  this  area  the  type  is  suited 
only  to  the  production  of  shallow-rooted  crops.  Grazing  and  dry 
farming  to  grain  are  the  principal  interests,  the  land  being  summer 
fallowed  every  other  year.  Owing  to  long-continued  grain  culture 
and  to  inadequacy  of  moisture  supply  occasioned  by  the  occurrence  of 
harclpan  near  the  surface,  light  yields  are  ol)tained  except  in  the  most 
favorable  seasons. 

The  following  table  gives  the  results  of  mechanical  analyses  of  the 
fine  earth  of  this  soil : 


Mechanical  analyses  of  Fl(ni  Joaquin  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
.  sand. 

Very  fine      ^-.^           .,, 
sand.     1      *^^^-           '-'^'^J- 

13072      ..  . 

Soil 

Subsoil 

Per  cent. 
1.0 
1.5 

Percent. 
6.6 
6.7 

Per  cent. 
6.0 

5.8 

Per  cent. 
16.7 
16.3 

Per  cent.  Per  cent. 
15.3            35.5 
16.7            33.0 

Per  cent. 
18  8 

13073 

19  9 

STOCKTON    SILT    LOAM. 


The  Stockton  silt  loam  is  subject  to  considerable  variation  in  depth 
of  soil  and  in  the  character  of  the  subsoil,  small,  widely  distributed 
])odies  of  fine  silty  loam  occurring  merely  as  superficial  deposits  over 
many  of  the  other  soils  of  the  area.  Typically,  however,  the  Stock- 
ton silt  loam  is  an  extensive,  important,  and  easily  distinguished  soil 
type,  consisting  of  a  fine,  friable  silty  loam  of  light-brown  color, 
extending  to  the  depth  of  G  feet  or  more,  and  becoming  somewhat 
lighter  in  color  and  texture  in  the  lower  section  of  the  profile. 
Although  loose  and  friable  when  in  proper  condition,  it  becomes 
sticky  when  wet  and  may  be  rendered  very  compact.  No  gravel  or 
other  coarse  material  appears  in  this  soil,  except  in  the  immediate 
vicinity  of  present  or  abandoned  stream  channels. 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,   CALIFORNIA. 


13 


The  Stockton  silt  loam  covers  a  considerable  area  in  the  north- 
eastern part  of  the  survey,  where  it  is  found  in  one  continuous  bod}' 
of  irregular  outline,  most  tyi)ically  developed  in  the  vicinity  of  the 
Calaveras  Eiver.  Other  small,  less  typical  bodies  occur  along  some 
of  the  other  streams  of  the  valley  plain.  The  surface  is  nearly  level 
and  without  variety,  save  for  an  occasional  grove  of  valley  oak  or  of 
willows  bordering  the  streams,  which  in  the  northeastern  part  of  the 
area  flow  in  deep  channels  with  vertical  banks.  The  soil  ]3asses 
gradually  into  the  Stockton  loam  and  somewhat  more  abruj)tly  into 
the  other  adjacent  tj'pes.  It  is  generally  well  drained,  percolation 
taking  place  readily,  but  with  proper  cultivation  is  capable  of  retain- 
ing a  large  supply  of  moisture. 

Material  derixinl  from  a  great  variety  of  rocks  probably  enters 
into  the  composition  of  the  Stockton  silt  loam.  ISIuch  of  the  fine 
silty  micaceous  material,  however,  is  believed  to  have  its  origin  in 
the  slates,  amphibolites,  and  other  altered  rocks  of  the  Sierra  Nevada 
Mountains,  transported  to  the  valley  and  distrilnited  by  flood  waters 
of  the  streams  in  recent  times. 

A  hardpan  of  calcareous  nature  is  sometimes  exposed  in  stream 
channels  cutting  this  type,  but  occurs  at  such  depths  as  hardly  to 
influence  the  growth  of  fruit  trees  or  ordinary  crops.  The  soil  is 
also  free  of  alkali  salts  in  injurious  quantities. 

The  Stockton  silt  loam  is  one  of  the  most  productive  soils  of  the 
area  and  is  well  adapted  to  tlie  growing  of  vegetables,  grains,  alfalfa, 
root  crops,  and  hard}^  fruits.  Hay  and  grain,  consisting  of  wheat, 
barley,  and  oats,  are  grown,  giving  good  yields  without  irrigation, 
under  proper  cultural  conditions.  Almonds,  cherries,  and  peaches 
also  yield  well.  Bramble  fruits,  grapes  for  table  and  winery  pur- 
poses, and  vegetables  are  grown  to  a  comparatively  small  extent,  but 
with  considerable  success. 

The  following  table  gives  the  results  of  mechanical  analyses  of  the 
Stockton  silt  loam: 

Mechanical  analyses  of  Stockton  silt  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium  1     Fine 
sand.        sand. 

Vervflne      ant 
sand.          ^*"- 

Clay. 

K3077 

Soil 

Per  cent. 

0  2 

Percent. 
0.9 

Per  cent. 

0.1 

.6 

Per  cent. 
.5.4 
5.4 

Per  cent. 
18.6 
19.6 

Per  cent. 
52.3 
53.1 

Percent. 
21.4 

i;»78 

Subsoil 

.0 

.6 

20.8 

FRESNO    SANDY   LOAM. 


The  Fresno  sandy  loam  varies  somewhat  in  texture  and  in  the  char- 
acter of  the  subsoil,  but  typically  the  surface  soil  consists  of  al)out  3 
feet  of  gray  to  light-brown  sandy  loam  of  medium  to  rather  fine  tex- 
ture, frequently  carrying  considerable  fine  angular  gravel  or  coarse 


14 


FIELD   OPERATIONS    OF    THE    BUREAU    OF    SOILS;    1905. 


sand  particles.  ^Vhile  usually  loose  and  friable,  the  soil  is  sticky 
when  wet  and  frequently  becomes  compact.  At  the  depth  of  3  feet 
this  soil  grades  into  a  fine  silty  loam  or  silty  clay  loam.  This  sub- 
soil also  frequently  carries  some  coarse  material,  is  of  a  light-yellow 
or  brown  color,  compact  structure,  and  smooth  and  somewhat  ashy 
texture,  sometimes  becoming  sandy  in  the  extreme  lower  part  of  the 
profile.  The  subsoil  frequentl}^  carries  concretions  and  is  underlain 
at  a  dejDth  of  about  5  feet  by  hardpan,  impenetrable  to  the  soil  auger 
or  ordinary  plant  roots. 

The  Fresno  sandy  loam  occurs  mainly  in  a  single  body  covering 
an  area  of  some  8  square  miles  lying  in  the  soatheastern  part  of  the 
area.  A  number  of  small  and  unimportant  bodies  also  occur  in  the 
vicinity  and  southeast  of  Lathrop  and  French  Camp.  The  surface 
is  level  or  onl}'  A^ery  slightly  rolling  and  is  generally  treeless.  Some 
of  the  smaller  bodies  occur  in  slight  depressions,  while  much  of  the 
larger  area  is  low,  flat,  and  somewhat  poorly  drained.  This  condi- 
tion is  augmented  in  places  by  the  occurrence  of  hardpan.  Consid- 
erable improvement  may  be  effected  in  the  case  of  the  depressions 
and  minor  sinks  b}'  artificial  drainage. 

The  Fresno  sand}'  loam  has  been  formed  by  the  deposition  of 
materials  derived  from  the  Sierra  Nevada  Mountains,  and  distrib- 
uted over  the  valley  plain  b}^  former  streams.  Considerable  granitic 
material  can  be  identified  in  the  soil.  Small  quantities  of  alkali 
salts  frequently  occur,  and  particularly  in  the  underlying  hardpan, 
which  not  infrequently  becomes  the  seat  of,  and  in  fact  probably 
owes  its  origin  somewhat  to,  the  especially  injurious  alkali  carbon- 
ates. While  the  quantity  of  these  salts  is  generally  not  excessive,  in 
a  few  cases  it  is  sufficient  to  prove  injurious  to  vegetation. 

With  irrigation  alfalfa,  fruits,  and  most  ordinary  farm  crops 
should  do  well  upon  this  soil  wherever  the  hardpan  does  not  ap- 
proach the  surface  too  closely.  At  present  grain  hay  and  grain  are 
grown,  without  the  aid  of  irrigation,  giving  fair  yields  in  favorable 
seasons.  The  growing  of  these  crops  and  of  alfalfa  under  irrigation 
is  becoming  more  important  from  year  to  year,  and  is  much  more 
profitable  than  under  the  old  system  of  dry  farming. 

The  following  table  gives  the  results  of  mechanical  anah^ses  of  a 
typical  sample  of  the  soil  and  subsoil  of  this  type: 

Mechanical  analyses  of  Fresno  sandy  loam. 


Number. 

Descrip- 
tion. 

Pine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Pine 
sand. 

Very  fine 
sand. 

Silt. 

.   Clay. 

13074 

Soil 

Subsoil.... 

Per  cent. 
2.9 
3.7 

Per  cent. 
13.2 
14.4 

Per  cent. 
6.5 
6.9 

Per  cent. 
17.1 
17.7 

Per  cent. 
16.7 
14.9 

Per  cent. 
31.1 
29.6 

Per  cent. 
12.4 

13075,13076 

12.5 

The  following  sample  contained  more  than  one-half  of  1  per  cent  of  calcium  carbonate 
(CaCOa)  :  No.  1307G,  2.18  per  cent. 


SOIL    SURVEY    OF   THE    STOCKTON    AREA,   CALIFORNIA. 


15 


FRESNO   FINE    SANDY   LOAM. 

The  Fresno  fine  sandy  loam  consists  of  6  feet  or  more  of  light-gi-ay 
sandy  loam  of  fine  ashy  texture  and  compact  structure.  The  soil  is 
very  smooth  and  quite  sticky  when  wet,  and  has  a  tendency  to  puddle. 
The  ashy  texture  and  compact  structure  are  most  evident  at  the 
depth  of  about  3  feet  or  3J  feet,  at  which  point  a  white  hardpan 
stratum  is  frequently  encountered.  The  extreme  lower  part  of  the 
soil  section  is  sometimes  considerably  lighter  in  texture  than  the 
overlying  soil. 

The  Fresno  fine  sandy  loam  is  not  an  extensive  soil  type.  It 
occurs  in  the  southern  part  of  the  survey  in  the  vicinity  of  French 
Camp,  Lathrop,  and  Atlanta,  usually  as  irregular  elongated  bodies 
extending  in  a  northwesterly  and  southeasterly  direction.  The  sur- 
face is  usually  low,  flat,  sometimes  slightly  depressed,  generally 
treeless,  and  without  distinctive  topographic  features.  Owing  to 
position  and  the  presence  of  hardpan,  natural  drainage  is  deficient 
and  percolation  is  arrested,  pools  of  water  frequently  remaining  in 
the  roads  and  fields  for  a  long  time  after  heavy  rains. 

The  origin  and  mode  of  formation  of  this  soil  is  essentially  the 
same  as  that  of  the  Fresno  sandy  loam,  the  material  being  of  a  finer 
grade.  As  in  that  type,  alkali  salts  in  small  quantities  are  of  gen- 
eral occurrence.  They  are  usually  found  in  the  underlying  hardpan 
or  compact  subsoil,  and  in  depressed,  poorly  drained  areas  have 
accumulated  at  the  surface  in  such  quantities  as  to  be  injurious  to 
ordinarv  farm  crops. 

A  considerable  area  of  the  Fresno  fine  sandy  loam  is,  in  its  present 
condition,  adapted  only  to  grazing.  In  those  sections  of  better 
natural  drainage  and  where  the  hardpan  is  less  impervious  or  con- 
tinuous or  lies  at  some  distance  below^  the  surface,  alfalfa,  grains, 
and  probably  vines  and  small  fruits  should  do  well  under  irrigation, 
if  care  be  taken  not  to  apply  excessive  quantities  of  water.  At 
present  the  type  is  devoted  mainly  to  grazing  and  to  dry-farming  to 
grains  and  grain  hay. 

The  following  table  gives  the  results  of  mechanical  analyses  of  a 
typical  sample  of  the  soil  and  the  subsoil  of  this  type : 

Mechanical  analyses  of  Fresno  fine  sandy  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

13053 

Soil 

Subsoil 

Percent. 

0.0 

.2 

Percent. 
2.3 
2.2 

Percent. 
6.6 
4.4 

Percent. 
37.1 
24.3 

Percent. 
24.1 
21.0 

Per  cent. 
21.1 
35.3 

Per  cent. 
8.8 

13054  

12.4 

The  following  sample  contained  more  than  one-half  of  1  per  cent  of  calcium  carbonate 
(CaCOs)  :  No.  13054,  1.36  per  cent. 


16 


FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS;    1905. 


FKESNO    SAND. 


The  Fresno  sand  consists  of  a  light-gray  or  light-brown  sand  of 
medium  texture  and  loose  incoherent  structure,  and  extends  to  a  depth 
of  G  or  more  feet.  The  soil  throughout  the  section  carries  consider- 
able coarse  angular  material. 

This  type  occurs  in  a  very  irregular  body,  with  relatively  long  and 
narrow  projections  extending  in  a  general  northwesterly  and  south- 
easterly direction  to  the  south  and  east  from  French  Camp  and 
Lathrop.  It  covers  a  considerable  area,  and  in  the  southern  part  of 
Twp.  1  S.,  R.  7  E.  it  is  the  prevailing  type  of  soil.  The  surface  is 
generally  slightly  rolling,  treeless,  and  unmarked  by  vegetation 
except  wild  grasses  and  a  great  variety  of  brilliantly  colored  wild 
flowers  appearing  during  the  early  spring.  The  soil  passes  gradu- 
ally into  the  adjacent  fine  sands  and  sandy  loams,  and  includes 
bodies  of  these  soils  too  small  to  be  shown  upon  the  majD. 

Owing  to  its  jDosition,  character  of  surface,  and  open,  porous  tex- 
ture, this  soil  is  naturally  very  well  drained.  Lower  lying  areas  and 
depressions  may,  however,  become  saturated  and  rendered  unproduc- 
tive from  a  too  copious  use  of  irrigation  waters  ujDon  the  higher 
slopes,  and  there  are  already  instances  of  impairment  of  the  lower 
lying  lands  from  this  cause. 

As  in  the  case  of  the  adjacent  soils  the  materials  forming  the 
Fresno  sand  originally  came  from  the  weathering  of  the  rocks  of 
the  Sierras.  The  w-ash  from  these  has  been  transported  by  streams 
and  distributed  over  the  valley  plain  in  gently  sloping  fanlike  forms. 
The  materials  forming  the  Fresno  sand,  however,  are  believed  to  be 
mainly  derived  from  granitic  rocks. 

Owing  to  the  good  natural  drainage  and  to  the  loose  open  structure 
of  the  soil,  it  is  free  from  injurious  alkali  salts.  The  soil,  how^ever, 
retains  little  moisture  and  therefore  is  hardly  a  satisfactory,  soil  for 
grain  or  shallow-rooted  crops  w^ithout  irrigation.  "Wliere  irrigated, 
it  is  well  adapted  to  alfalfa  and  general  forage  crops.  Cherries, 
peaches,  small  fruits,  and  early  truck  crops  would  also  prove  profit- 
able. Alfalfa  and  grain  are  the  principal  crops  grown  at  present. 
Alfalfa,  which  is  growai  w^ith  the  aid  of  irrigation,  yields  well.  The 
yield  of  grain,  dry-farmed,  is  generally  very  light. 

The  following  table  gives  the  results  of  mechanical  analyses  of  a 
typical  samj^le  of  the  soil  and  the  subsoil  of  this  type : 

Mechanlcul  unahjucs  of  Fresno  sand. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Pine 
sand. 

Very  fine      a,.,^. 
sand.         ^'1*- 

Clay. 

13049 

Soil 

Subsoil 

Per  cent. 
5.6 
1.9 

Per  cent. 
23.7 
19.9 

Per  cent. 
19.8 
18.6 

Per  cent. 
30.4 
34.3 

Per  cent. 
12.3 
15.9 

Per  cent. 
4.8 
5.7 

Per  cent. 
3.0 

13050 

3.7 

SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA. 


17 


I'RKSNo  finf:  sand. 


The  Fivsno  fine  sand  consists  t^'pically  of  a  light-yolloAV  or  light- 
broAvn  niicacoous  sand  of  fine,  smooth  texture  and  ()[)en,  porous  struc- 
ture, extending  to  the  depth  of  G  or  more  feet.  In  the  Fresno  fine 
sand  of  the  Stockton  area  the  lower  part  of  the  soil  section  is  fre- 
quentl}'  slightly  heavier  and  somewhat  more  tenacious  when  wet  than 
nearer  the  surface.  It  is  usually  free  from  gravel  or  other  coarse 
material,  except  where  there  is  an  achnixturc  of  the  adjacent  Fresno 
sand. 

The  Fresno  fine  sand  is  found  in  several  huig,  narrow  areas  asso- 
ciated with  the  Fresno  sand  and  Fresno  fine  .sand}^  loam  south  and 
southeast  of  French  Camp,  'i'iie  surface  is  generally  nearly  level  or 
only  slightly  uneven.  The  native  vegetation  is  similar  to  that  of  the 
Fresno  sand,  consisting  of  grasses  and  flowering  weeds. 

While  the  areas  of  Fresno  fine  sand  are  only  slightly  above  adja- 
cent soils  of  somewhat  deficient  drainage,  percolation,  evai)oration, 
and  lateral  movement  of  the  soil  water  is  ra])id.  The  soil  is  somewhat 
deficient  in  moisture-retaining  i)r()perties,  and  frequent  cultivation 
becomes  of  great  importance  in  conserving  moisture  for  the  use  of 
the  crops. 

In  origin  and  mode  of  formation  the  Fresno  fine  sand  is  similar  to 
the  P'resno  sand,  micaceous  granitic  material  predominating.  It  is 
free  from  alkali  salts  in  injurious  quantities,  although  the  deeper 
subsoil  contains  small  quantities,  which  under  excessive  irrigation, 
coupled  with  insufficient  cultivation  and  drainage,  might  in  time 
become  concentrated  at  the  surface  in  sufficient  amounts  to  prove 
injurious  to  ordinary  crops.  There  is  generally  no  hardpan  forma- 
tion in  this  soil  within  the  depth  of  6  feet. 

The  Fresno  fine  sand  is  best  adapted  to  the  growing,  under  irri- 
gation, of  alfalfa,  forage  crops,  or  hardy  fruits,  requiring  a  loose, 
well-drained  soil.  It  is  generally  devoted  at  present  to  grazing  and 
to  the  growing  of  alfalfa  and  grain  with  and  without  irrigation,  the 
yields  being  generally  slightly  better  than  those  obtained  from  the 
Fresno  sand.  This  is  especially  true  in  the  case  of  the  dry-farmed 
areas. 

The  following  table  gives  the  results  of  mechanical  analyses  of  a 
typical  sample  of  the  soil  and  the  subsoil  of  this  type: 

Meclnniicdl  iiiiali/sfS!  of  Fresno  piic  sniiil. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very fine 
sand. 

Silt. 

Clay. 

13051 

13052 

Soil 

Subsoil .... 

Per  cent. 
0.9 

.7 

Per  cent. 
6.2 
5.9 

Percent. 
S.5 
9.1 

Per  rent.  Per  cent. 

34.6  !       .  28.3 

34.7  1          28.7 

Per  cent. 

15.8 
1.5.8 

Per  cent. 
5.6 
5.0 

1.^^17— 

OC,  Ai 3 

18 


FIELD    OPER.\TIONS    OF    THE    BUREAU    OF    SOILS^    1905. 


SAN    JOAQUIN    SANDY    LOAM. 

The  San  Joaquin  sandy  loam  consists  of  about  30  inches  of  sandy 
loam  of  medium  texture  and  of  light-red  color,  underlain  by  an  im- 
penetrable hardpan  of  fine  texture  and  dense  structure.  The  coarser 
particles  in  the  soil  are  angular  and  sharp  and  tend  to  give  it  a  fri- 
able structure  when  in  a  favorable  condition,  but  when  wet  the 
materials  become  sticky,  with  a  tendency  toward  puddling  and  bak- 
ing. The  lower  part  of  the  soil  becomes  slightly  heavier  in  texture 
and  more  compact  in  structure,  the  4  inches  immediately  above  the 
hardpan  containing  considerable  clay  and  exhibiting  the  structure  of 
adobe.  AMiile  the  average  thickness  of  the  soil  covering  is  30  inches, 
the  depth  to  hardpan  is  subject  to  some  variation. 

This  soil  occurs  only  in  a  single  extensive  and  uniform  body  east 
of  Ellisworth  in  the  southeastern  part  of  the  area.  The  surface  is 
treeless,  except  in  the  vicinity  of  minor  stream  channels,  is  sometimes 
marked  by  slight  depressions,  and  slopes,  in  general,  slightly  to  the 
northwest.  While  occupying  a  more  favorable  position  for  drainage 
than  many  of  the  soils  of  the  area,  as  in  the  case  of  the  San  Joaquin 
loam,  the  percolation  is  checked  by  the  underlying  hardpan,  and 
drainage  in  the  lower  depressions  and  in  areas  of  slight  inclination  is 
deficient. 

The  San  Joaquin  sandy  loam  owes  its  origin  probably  to  deposi- 
tion of  the  material  originating  in  the  rocks  of  the  Sierra  Xevada 
Mountains,  in  the  waters  of  an  ancient  Pleistocene  lake  or  bay,  the 
material  being  modified  by  later  alluvial  wash  and  by  the  secondary 
hardpan  formation.  Alkali  is  not  found  in  injurious  quantities  in 
the  soil. 

Owing  to  the  j^resence  of  hardpan  the  San  Joaquin  sandy  loam  is 
not  adapted  to  fruit  trees,  alfalfa,  or  other  deep-rooted  or  heavily 
irrigated  crops.  ""Grain  hay  and  grains,  grown  without  the  aid  of 
irrigation,  are  the  principal  crops,  the  yields  being  fair  in  favorable 
seasons. 

The  following  table  gives  the  results  of  mechanical  analyses  of  a 
typical  sample  of  the  soil  and  the  subsoil  of  this  type : 

Mechanical  dixili/scs  of  »S'rt;(  JocKjiiin  i^audi/  loam. 


Number. 

Description. 

Pine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

13a59 

Soil 

Subsoil 

Per  cent. 
4.5 

2.8 

Per  cent. 
■     18.9 

16.  r 

Per  cent. 
8.9 
8.5 

Per  cent. 
1.5.5 
15.7 

Per  cent. 
14.8 
13.5 

Per  cent. 
25.4 
23.6 

Per  cent. 
12  3 

13060.. 

18  8 

STOCKTON   LOAM. 


The  Stockton  loam  is  subject  to  considerable  variation  in  color, 
texture,  and  character  of  soil  and  subsoil.  Typically  it  consists  of  6 
or  more  feet  of  light  chocolate-brown  to  nearly  black  loam  of  medium 


SOIL    SURVEY    OF    TH?:    STOCKTON    AREA,   CALIFORNIA.  19 

texture  and  of  soiuewliat  (•()nii)act  structure.  The  lower  portion  of 
the  section  is  somewhat  li<rhter  in  coh)r  and  frequently  in  texture, 
although  the  subsoil  fre(iucntly  becomes  a  fine  silty  loam.  The  soil 
is  easily  cultivated  and  friable  when  in  proper  moisture  condition, 
but  becomes  sticky  when  wet  and  has  a  tendency  to  puddle.  Limited 
areas  occur  in  which  the  texture  and  structure  of  the  soil  approaches 
that  of  the  adjacent  soil,  the  Stockton  loam  blending  with  the  other 
types. 

The  Stockton  loam  is  a  type  of  considerable  extent  and  importance, 
occurring  in  ii-rcgular  bodies  in  the  central  and  eastern  i)arts  of  the 
survey.  The  larger  and  most  typical  areas  occur  northeast  of  Stock- 
ton and  in  the  vicinity  of  Waterloo  and  Linden.  Small  elongated 
bodies  frequently  occur  along  streams  in  other  parts  of  the  area.  The 
surface  is  usually  level  or  only  slightly  uneven,  and  elevated  but  little 
above  the  adjacent  heavier  soils.  Drainage  is  sometimes  deficient 
during  seasons  of  hea\'y  rains,  but  in  general  the  conditions  are  satis- 
factory during  the  growing  and  harvesting  seasons.  A  few  slight 
depressions  occur  which  would  be  benefited  by  artificial  drainage. 

A  light  sandy  phase  of  this  soil  occurs,  in  which  the  upper  3  feet 
consists  of  a  light  loam  of  dark  or  black  color,  containing  a  large 
amount  of  rather  coarse,  loose  sand.  This  is  underlain  at  about  3 
feet  by  the  loam  of  fine  silty  texture  and  light  color  which  is  found 
in  the  typical  soil.  This  phase  occurs  as  occasional  streaks  or  as  slight 
mounds  or  ridges,  usually  in  the  vicinity  of  former  or  present  stream 
channels.  The  largest  area  is  found  near  the  northern  margin  of  the 
area  about  7  miles  northwest  of  the  center  of  the  city  of  Stockton.  It 
is  generally  well  drained,  free  from  alkali,  somewhat  less  retentive 
of  moisture  thaii  the  typical  soil,  but  similar  in  other  important 
features. 

Like  the  adjacent  soils  of  the  valley  floor,  the  Stockton  loam  is  of 
alluvial  origin,  resulting  from  the  deposition  of  heterogeneous  sedi- 
ments, in  ancient  lakes  or  bays,  and  streams,  modified  by  an  admix- 
ture of  more  recent  sediments  laid  down  by  existing  streams.  It  pos- 
sesses in  a  high  degree  the  power  to  retain  moisture,  and  under  proper 
cultivation  may  be  rendered  capable  of  supplj'ing  the  needs  of  crops 
during  long  periods  of  drought.  It  is  also  generally  free  from  alkali 
salts,  although  small  patches  occasionally  occur  in  a  few  districts  of 
deficient  drainage,  where  the  salts  have  become  concentrated  in  inju- 
rious quantities  at  or  near  the  surface.  Such  alkali  areas  are,  how- 
ever, in  the  aggregate  of  but  relatively  small  extent. 

The  Stockton  loam  is  well  adapted  to  the  growing  of  small  and 
stone  fruits  suited  to  the  climate,  and  also  to  alfalfa,  onions,  cabbage, 
and  other  vegetables,  grain,  and  grain  hay.  At  present  the  two  crops 
last  named,  grown  without  irrigation,  are  the  principal  products. 
The  yields  are  generally  good,  unless  reduced  by  unfavorable  seasons. 
To  some  extent  vegetables  and  fruits  are  also  grown  with  profit  in 
the  vicinitv  of  Stockton. 


20 


FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS^    1905. 


The  followiiio-  table  gives  the  results  of  mechanical  analyses  of  a 
typical  sample  of  the  soil  and  the  subsoil  of  this  type : 

AJcchanical  (nialijses  of  Stockton  loam. 


Number.        Description. 


1305.5. 
13056. 


Soil _. 

Subsoil 


Fine 
gravel. 


Percent. 

0.5 

.1 


Coarse 
sand. 


Per  cent. 
5.3 
7.3 


Medium :     Pine 
sand.         sand. 


Per  cent. 

8.4 

■      12.8 


Very  fine 
sand. 


Percent.  Percent. 
25.4  ;  18.7 

31.2  I  17.0 


Silt. 


Percent. 
22.2 

18.8 


Clay. 


Percent. 
19.9 
13.2 


STOCKTON    LOAM    ADOBE. 


The  soil  of  the  Stockton  loam  adobe  consists  of  a  heavy,  Ijlack  clay 
loam  adobe,  extending  to  the  depth  of  about  30  inches,  and  containing 
a  considerable  admixture  of  sand,  consisting  mainly  of  coarse  angular 
white  particles.  This  is  "underlain  to  a  depth  of  6  or  more  feet  by  a 
fine  silty  or  silty  clay  loam  of  light-yellow  color.  The  soil  is  of  a  very 
dense  compact  structure  and  frequently  checked  upon  the  surface. 
It  becomes  very  sticky  when  wet,  and  unless  properly  cultivated 
puddles  readily  and  bakes  upon  exposure. 

The  Stockton  loam  adobe  occurs  only  in  a  single  body,  and  that  of 
limited  extent,  lying  north  of  Stockton  and  along  the  northern  margin 
of  the  area.  The  surface  is  generally  nearly  level  or  only  slightly 
uneven,  and  marked  by  an  occasional  clump  of  valley  oak  or  by  wil- 
lows in  the  vicinity  of  stream  channels.  By  gradual  diminution  in 
the  proportion  of  sand  the  soil  grades  into  the  other  adobe  lands 
lying  to  the  south. 

Owing  to  relatively  low  j^osition  and  to  the  compact  structure  and 
heavy  texture  of  the  soil,  natural  drainage  is  frequently  deficient, 
especially  during  and  following  seasons  of  heavy  rains.  Artificial 
drainage  is  sometimes  resorted  to  and  might  be  further  extended  with 
beneficial  results. 

Deposits  from  ancient  lakes  or  bays  with  the  later  addition  of  sedi- 
ments from  streams,  modified  by  the  various  agencies  of  Aveathering, 
have  given  rise  to  this  soil.  The  original  materials  have  been  derived 
from  a  great  variety  of  rocks,  as  in  the  case  of  nearly  all  the  soils  of 
the  area.  No  hardpan  formation  seems  to  occur  and  alkali  salts  only 
in  very  small  quantities,  though  the  latter  are  sufficient  to  increase 
.somewhat  the  tendency  of  the  soil  to  puddle.  The  fields  are  marked 
by  small  light-colored  spots,  which  appear  upon  cultivation  and  are 
believed  to  be  due  to  peculiarities  of  physical  structure,  probably 
induced  by  the  action  of  small  quantities  of  soluble  salts.  These  light- 
colored  spots  are  frequently  less  productive  than  the  rest  of  the  field. 

This  soil  is  probably  best  adapted  to  grazing  and  the  growing  of 
alfalfa^  grain,  hay,  and  foi-age  crops,  the  purposes  for  which  it  is  at 
present  used. 


SOIL    SURVEY    OB^    THE    STOCKTON    AREA,    CALIFORNIA. 


21 


The   f()llowin<i-  lal>le   oivo  the   resuks  of  ineehanieal   analyses  of 
typical  samples  of  the  Stoekton  loam  adobe  : 

Mechanical  analyses  of  Siuckton  loam  adobe. 


Number.        j  Description, 


1301)1 :  Soil 

13063 Subsoil 


Fine        Coarse  j  Medixim      Fine      Very  line      cjj^ 
gravel.       sand.        sand.         sand.    '    sand. 


Per  cent. 

0.5 

.6 


Per  cent.  Per  cent.'  Per  cent.l  Per  cent. 
3.0  3.2  I         15.2  I         21.6 

3.0  '  2.9  15.1  20.6 


Clay. 


Per  cent. 
30.8 
«.3 


Per  cent. 
25.9 
14.8 


The  followins;  samples  contained  more  than  one-half  of  1  per  cent  of  calcium  carbonate 
(CaCOa)  :   No.  laOGl,  1.45  per  cent;   No.  i;i()fi2,  2.18  per  cent. 


STOCKTON    CLAY    ADOBE. 


'J'he  Stockton  clay  adobe  consists  of  a  chocolate-brown  to  nearly 
black  heavy  clay  adobe,  with  a  depth  of  about  36  inches,  and  under- 
lain to  a  depth  of  6  or  more  feet  by  a  light-j^ellow  subsoil  of  fine, 
silty  cla}'^  texture.  The  soil  is  of  close  compact  structure,  polishing 
Iiighly  upon  the  soil  auger,  is  exceedingly  tenacious  and  of  a  stiff 
puttylike  consistency  when  wet,  checking  at  the  surface  into  large 
blocks  by  deep  surface  cracks  upon  exposure.  In  advanced  stages  of 
checking,  the  larger  blocks  are  divided  and  subdivided  by  smaller 
checks  and  cracks,  causing  the  surface  to  break  up  on  cultivation  into 
a  loose  mass  of  small  blocks  and  pellets  of  the  size  of  small  peas  and 
larger. 

The  subsoil  is  of  much  less  dense  and  compact  structure  than  the 
soil,  but  is  very  sticky  when  wet  and  frequently  carries  small  rounded 
concretions  or  incipient  hardpan  formation.  Both  soil  and  subsoil 
frequently  contain  small  subangular  rock  particles  of  the  size  of  fine 
gravel. 

The  more  extensive  and  typical  bodies  of  the  Stockton  clay  adobe 
occur  near  the  eastern  part  of  the  area,  in  the  vicinity  of  Elliswortli 
and  Collegeville.  Many  smaller  irregular  bodies  are,  however,  scat- 
tered throughout  the  eastern  half  of  the  survey.  The  surface  is  low, 
nearly  level,  and  without  distinctive  natural  features,  except  for  an 
occasional  growth  of  valley  oak.  The  soil  grades  into  the  adjacent 
loams  and  the  heavy  and  dense  Stockton  clay  loam  adobe.  Owing 
to  unfavorable  position  and  to  the  dense,  heavy  nature  of  the  soil, 
natural  drainage  is  generally  deficient  during  the  rainy  seasons,  farm 
operations  and  even  travel  over  the  roads  being  greatly  hampered  or 
temporarily  suspended. 

The  Stockton  clay  adobe  in  the  main  owes  its  origin  to  the  distribu- 
tion over  the  valley  floor  of  very  finely  divided  rock  material,  derived 
from  a  great  variety  of  rocks  and  modified  by  an  admixture  of 
ancient  Pleistocene  sediments. 

Owing  to  the, texture  and  structure  of  the  soil,  percolation  is 
arrested  and  the  soil  when  dry  absorbs  water  very  slowly.     It  is, 


22 


FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,    1905. 


however,  capable  of  holding  a  great  amount  of  water  when  satur- 
ated, which  is  slowly  given  up  under  evaporation.  Under  proper 
methods  of  cultivation  it  is  thus  able  to  retain  much  moisture 
throughout  the  dry  summer  seasons,  and  to  supply  the  crop  needs 
during  prolonged  droughts.  The  soil  is  also  generally  free  from 
impervious  hardpan  or  alkali  salts  in  such  quantities  as  to  become 
detrimental  to  crops.  The  small  light-colored  spots  noted  in  the 
description  of  the  Stockton  loam  adobe  are  also  of  frequent  occur- 
rence in  the  type  under  discussion. 

This  soil  is  not  generally  w^ell  adapted  to  early  vegetables  or  fruits, 
or  to  croj^s  requiring  a  light,  well-drained  soil.  It  is  best  suited  to 
the  production  of  alfalfa,  forage  crop-^,  grain,  and  grain  hay.  Dairy- 
ing and  stock  raising  should  be  profitable  industries  where  the  tramp- 
ling of  the  soil  in  wet  seasons  by  stock  can  be  avoided.  Alfalfa, 
grain  hay,  and  grain  are  the  principal  crops  now  grown,  the  yields 
being  generally  good  or  relatively  heavy  in  favorable  seasons.  Vines, 
tree  fruits,  and  vegetables  are  grown  to  a  limited  extent  upon  lighter 
phases  of  the  t3'pe  in  the  district  lying  northeast  of  Stockton,  with 
fair  yields  under  careful  cultivation  and  attention. 

The  following  table  gives  the  results  of  mechanical  analyses  of 
typical  samples  of  the  soil  and  the  subsoil  of  this  type : 

Mechanical  analijsrx  of  Stockton  chty  adobe. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

ll^OS^             

Soil 

Per  cent. 
0.4 

Per  cent. 
1.5 

Per  cent. 
1.6 
1.9 

Per  cent. 
7.5 
8.1 

Per  cent. 
12.3 
13.0 

Per  cent. 
36.4 
33.1 

Per  cent. 
40.2 

13064 

Subsoil 

.3 

1.9 

42.3 

STOCKTON    CLAY    LOAM    ADOBE. 


The  Stockton  clay  loam  adobe  consists  of  a  black  clay  loam  adobe, 
similar  in  structure  features  to  the  Stockton  clay  adobe,  but  of 
smoother  texture,  being  generally  free  from  coarse  or  gritty  material. 
It  polishes  highly  upon  the  soil  auger  and  assumes  an  exceedingly 
tenacious,  w^axy  or  stiff,  puttylike  consistency  when  wet.  During  the 
dry  season  the  checking  of  the  surface  is  often  developed  to  a  re- 
markable degree.  It  is  underlain  at  aI)out  8  feet  by  a  yellow  heavy 
silt}^  or  silty  clay  subsoil,  becoming  lighter  in  the  lower  part  of  the 
section  and  similar  to  that  of. the  Stockton  clay  adobe.  The  surface 
of  the  subsoil  in  the  more  southerly  lying  bodies  is  frequently  some- 
what comj)acted  and  j^artially  cemented  immediately  below  the  over- 
lying soil  into  a  soft,  iuiperfect  hardpan  or  separated  from  the  over- 
lying soil  by  a  thin  white  crust  of  relatively  soft,  calcareous  hardpan. 

The  Stockton  clay  loam  adobe  is  one  of  the  most  important  soils 
of  the  area,  occurring  in  the  most  extensive  and  typfcal  bodies  to  the 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA. 


23 


north,  south,  and  east  of  Stockton.  The  surface  is  h)w,  level,  and 
without  topographic  variety.  An  occasional  grove  of  valley  oak 
appears,  but  much  less  frequently  than  upon  the  adjacent  soils  of 
lighter  texture  and  more  open  structure. 

As  in  the  Stockton  clay  adolie,  the  natural  drainage  is  poor,  the  soil 
becoming  uncultivable  during  wet  seasons.  The  mode  of  formation 
of  this  soil  is  somewhat  obscure.  The  materials  constituting  it  are 
probably  derived  from  a  great  variety  of  rocks,  and  have  been  dis- 
tributed by  the  waters  of  streams  and  tides  and  modified  by  the 
incorporation  and  decomposition  of  vegetable  matter.  It  is  gener- 
ally free  from  alkali  salts  in  injurious  quantities,  and  in  its  pro- 
nounced moisture-retaining  properties  is  very  similar  to  the  Stock- 
ton clay  adobe. 

Like  the  Stockton  clay  adobe  also,  it  is  best  adapted  to  alfalfa, 
grass  and  forage  crops,  and  grains,  which  crops  are  at  present  the 
principal  ones  grown.  The  yields  are  generally  good,  unless  proper 
preparation  of  the  land  is  prevented  by  unfavorable  weather  and 
drainage  conditions,  or  the  growth  of  the  crop  is  retarded  by  the  rav- 
ages of  fungous  diseases  or  insect  pests,  the  development  of  rust  or 
other  fungus  sometimes  being  induced  by  the  wet  conditions  in  the 
low-lying  areas. 

The  following  table  gives  the  average  results  of  mechanical  analy- 
ses of  typical  samples  of  the  soil  and  the  subsoil  of  this  type : 

Mecltanicdl  (niali/scs  of  Stockton  vJay  Joani  adobe. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

13066. 

Soil 

Subsoil 

Per  cent. 

0.5 

.5 

Per  cent. 
1.3 
1.6 

Per  cent. 
2.0 
2.1 

Per  cent. 
12.3 
17.1 

Per  cent. 
17.9 
20.3 

Per  cent. 
35.0 
34.4 

Per  cent. 
30.9 

13067,13068 

2,3.7 

SACRAMENTO     CLAY    LOAM. 


The  Sacramento  clay  loam  occurs  typically  as  a  dark-colored,  nearly 
black  heavy  silty  clay  loam,  containing  a  large  proportion  of  organic 
matter,  the  remains  of  decaying  vegetation.  The  soil  generally 
extends  to  the  depth  of  about  30  inches.  The  proportion  of  organic 
matter  is  usually,  but  not  always,  less  in  the  first  few  inches  than  in 
the  lower  part  of  the  soil  section.  Vegetable  fiber  is  of  frequent 
occurrence,  but  the  greater  part  of  the  organic  matter  is  thoroughly 
decomposed.  The  dark-colored  soil  is  underlain  by  a  light-yellow 
fine  silty  loam,  frequently  grading  into  a  very  fine  sandy  loam,  and 
extending  to  the  depth  of  O  or  more  feet.  Both  soil  and  subsoil  are 
free  from  gravel  or  other  coarse  material,  of  somewhat  compact  struc- 
ture, sticky  when  wet,  but  friable  under  cultivation. 


24         fip:ld  ()Pp:rations  of  the  bureau  of  soils,  lOOo. 

The  type  is  subject  to  considerable  variation  in  depth,  texture,  char- 
acter of  subsoil,  and  in  the  relative  amounts  of  silt  and  organic  mat- 
ter. In  the  vicinity  of  the  adjacent  peat  lands  it  is  underlain  by  the 
partially  decomposed  peat  instead  of  by  the  yellow  silty  loam  sub- 
soil, as  described.  A  silty  clay  phase  also  occurs  in  a  few  small  areas 
in  the  vicinity  of  the  San  Joaquin  River  and  some  of  its  larger  tribu- 
taries. This  phase  consists  of  a  deposit  of  from  a  few  inches  to  2 
feet  or  more  of  a  light  yellow,  very  fine,  heavy  silty  or  silty  clay  loam, 
very  sticky  when  wet,  and  of  rather  compact,  dense  structure,  imder- 
lain  by  the  peaty  and  silty  loam  materials  of  the  typical  soil.  It  is 
similar  to  the  typical  soil  in  most  other  particulars,  but  is  of  a  more 
refractory,  denser  texture  and  structure  and  requires  more  careful 
preparation  and  cultivation. 

The  Sacramento  clay  loam  is  an  extensive  and  important  soil  type, 
occurring  in  the  central  and  southwestern  parts  of  the  area.  The  sur- 
face is  generally  level  or  only  slightly  inclined,  and  treeless,  except 
in  the  vicinity  of  the  streams.  The  depressions,  which  are  of  defi- 
cient drainage,  are  usually  marked  by  a  growth  of  tules  or  rushes. 
The  soil  jjasses  gradually  into  the  adjacent  peat  lands,  adobes,  and 
loams. 

f  Percolation  is  sometimes  retarded  by  the  compact  structure  of  the 
subsoil,  which,  with  the  low-lying  position  and  gentle  slope,  often 
results  in  insufficient  natural  drainage,  and  open  drainage  ditches  are 
frequently  encountered  in  the  cultivated  areas  of  this  type. 

The  Sacramento  clay  loam  owes  its  origin  to  the  admixture  of  the 
fine  river  silts,  derived  from  a  variety  of  rocks  and  distributed  by  the 
San  Joaquin  River  and  its  tributaries  and  branches,  with  the  fine 
alluvial  and  decomposed  organic  matter  of  the  tidal  fresh-w^ater 
marshes  or  peat  lands.  The  material  from  these  two  sources  is  either 
intimately  mixed  or  deposited  in  alternating  strata.  The  soil  is  gen- 
erally free  from  alkali  salts  in  injurious  quantities,  and  under  proper 
cultivation  possesses  valuable  moisture-retaining  properties. 

While  containing  a  large  amount  of  organic  plant  food,  and  gen- 
erally productive,  the  crop  yields  decline  where  a  single  crop  is  grown 
continuously.  When  the  water  ta})le  is  not  too  close  to  the  surface, 
the  type  is  best  adapted  to  alfalfa,  to  grass  and  forage  crops — such 
as  redtop,  rye  grass,  timothy,  some  of  the  clovers — and  to  root  crops, 
beans,  vegetables,  and  grain.  Much  of  this  land  is  admirably  adapted- 
to  dairying  and  stock  raising.  Small  and  tree  fruits,  consisting  of 
peaches,  apricots,  pears,  and  cherries,  also  do  well  in  the  higher  and 
better  drained  areas  of  lighter  texture. 

(irain  hay  and  grain,  consisting  of  wheat,  barley,  and  oats,  are  the 
principal  crops,  the  yields  being  usually  good.  Alfalfa,  in  connection 
Avitli  dairying  and  stock  raising,  is  also  grown  in  limited  (juantities. 
In  small,  fa\()ral)ly  situated  Ixxlies.  esj>ccialh^  in  the  vicinity  of  the 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,   CALIFORNIA. 


25 


San  Joaquin  River,  fruit  and  vegetable  production  is  of  considerable 
importance  and  profit. 

The  following  table  gives  the  results  of  mechanical  analyses  of 
typical  samples  of  the  soil  and  subsoil  of  this  type : 

Mechanical  analyses  of  Sacramento  clay  loam. 


Number. 

Description. 

Fine       Coarse    Medium      Fine      Very  fine 
gravel.  '    sand.        sand.        sand.        sand. 

Silt. 

Clay. 

v.mi 

Soil 

Per  cent. 
0.3 

Per  cent. 

0.8 

.8 

Per  cent. 

0.5 

.4 

Per  cent. 
2.5 
9.0 

Per  ce7it. 

6.3 

36.2 

Per  cent. 
40.3 
46.5 

Per  cent. 
49.7 

13(>->8 

Subsoil 

.5 

16.6 

The  following  sample  contained  more  than  one-half  of  1  per  cent  of  calcium  carbonate 
(CaCOa)  :  No.  13058,  1.36  per  cent. 


In  point  of  extent  of  area  covered,  naturally  unproductive  condi- 
tion, progress  of  reclamation  operations,  and  agi'icultural  possibili- 
ties, the  Peat  lands  of  the  Stockton  area  are  of  great  interest  and 
importance. 

In  typical  section  the  soil  consists  of  6  feet  or  more  of  fine  alluvial 
river  and  tidal  silts,  intimately  commingled  with  partially  decayed 
vegetable  matter,  undecomposed  plant  roots,  stems,  and  fibers  occur- 
ring in  great  profusion..  This  material  is  dark  brown  to  black,  of  an 
exceedingly  smooth  and  pasty  consistency  when  wet,  of  spongy  tex- 
ture, and  generally  saturated  with  water  at  a  depth  of  2  or  3  feet  or 
less.  In  certain  districts  subjected  to  recent  overflow  by  streams  in 
flood,  the  surface  foot  frequently  consists  largely  of  river  silts,  in 
which  the  usual  proportion  of  organic  matter  is  greatly  decreased. 
The  subsoil  is,  however,  the  same. 

The  depth  of  the  Peat  is  also  subject  to  considerable  variation, 
usuallj^  increasing  in  the  direction  of  the  lower  San  Joaquin  River, 
which  leaves  the  area  near  the  northwestern  extremity.  Near  the 
margins  of  the  soil  bodies  it  is  frequently  underlain  at  a  depth  of 
from  4  to  G  feet  by  a  stratum  of  sand3;^lay  of  bluish  cast,^-  by  com- 
pact river  silts  and  fine  sands,  though  a\'er  the  greater  proportion  of 
theTsoil  areaflie  iiiulerlying  light-colored  fine  river  sands  are  encoun- 
tered only  at  a  depth  of  from  10  to  15  feet  or  more,  while  in  the  north- 
western portion  of  the  area  the  depth  of  the  peaty  deposits  is  much 
greater.  In  parts  of  this  latter  mentioned  section  only  the  immediate 
crust  is  of  sufficient  solidity  and  toughness  to  bear  the  weight  of  farm 
animals  or  machinery,  the  underlying  material  being  in  an  exceed- 
ingly soft  semifluid  condition,  and  extending  to  great  depths. 

Although  quite  sticky  when  wet,  there  is  but  little  or  no  tendency 
toward  puddling,  the  surface  being  friable  and  easily  cultivated  after 
the  first  breaking  or  cutting  away  of  the  surface  accumulation  of  the 


II 


26  FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,   1905. 

tough  roots  of  aquatic  plants.     No  gravel  or  other  coarse  material 
appears  in  either  soil  or  subsoil. 

This  important  soil  type  occurs  only  in  the  San  Joaquin  River  delta 
region,  where  it  covers  the  greater  proportion  of  the  entire  western  half 
of  the  area  surveyed.  The  topographic  and  drainage  features,  min- 
eralogical  origin,  and  mode  of  formation  are  much  the  same  as  in  the 
other  soils  of  the  lower  delta.  The  drainage  conditions  will  be  dis- 
cussed more  particularly  under  the  succeeding  heading. 

Extreme  lightness  in  weight  constitutes  a  very  striking  feature  of 
the  Peat,  large  fragments  frequently  becoming  detached  and  floating 
about  with  the  stream  and  tidal  currents. 

The  soil  carries  a  great  supply  of  plant  food  and  under  favorable 
conditions  yields  enormously.  This  has  given  rise  to  the  belief  that 
the  soil  is  capable  of  continuousl}^  producing  all  manner  of  crops, 
without  regard  to  the  principles  of  ordinary  farm  management  or 
crop  rotation.  This  belief  is  not  borne  out  by  agricultural  practice. 
"While  ranking  among  the  most  productive  soils  known  and  while 
maintaining  this  productiveness,  when  farmed  under  ordinary,  care- 
ful, modern  methods,  the  long-continued  growing  of  successive  crops 
of  grain,  as  in  the  case  of  other  soils,  is  resulting  in  decreased  pro- 
duction. \^he  profitable  growing  of  successive  crops  of  potatoes  is 
said  to  DC  limited  to  three  or  four  years. 
L'  The  accidental  ignition  of  the  Peat  from  "  tule  fires,"  or  in  other 
^ways,  often  proves  troublesome,  the  organic  material  of  the  soil 
slowly  smoldering  until  practically  removed,  unless  the  fire  ^e 
checked  by  flooding.  This  leaves  the  soil  a  mere  bed  of  red  or  light- 
colored  ash,  and  greatly  reduces  its  value,  and,  moreover,  increases 
capillary  movement  and  rapid  evaporation  from  the  surface,  resulting 
frequently  in  the  surface  accumulation  of  alkali  salts  in  injurious 
quantities.  T^Hien  not  modified  by  ignition,  the  capillary  or  upward 
movement  of  soil  waters  takes  place  so  slowly  that  the  application  of 
irrigation  waters  to  the  soil  surface  frequently  becomes  necessary 
during  the  dry  season,  although  the  soil  may  be  saturated  with  water 
at  the  depth  of  3  or  4  feet,  or  even  less. 

While  alkali  salts  exist  in  these  soils  and  in  the  surface  waters  in 
considerable  amounts,  under  ordinary  conditions  they  are  not  of  suf- 
ficent  concentration  to  become  injurious  to  ordinary  crops,  and  their 
accumulation  in  harmful  quantities  takes  place  only  through  the 
destruction  of  the  natural,  coarse,  mulchlike  structure  of  the  soil. 

The  Peat  is  generally  ill  adapted  to  the  growing  of  alfalfa  or  other 

deep-rooted  crops,  owing  to  the  close  approach  to  the  surface  of  the 

water  table.     On  the  other  hand,  it  is  admirably  adapted  to  certain 

I  special  crops,  such  as  asparagus,  beans,  onions,  or  other  vegetables, 

/  forage  crops,  timothy,  redtop,  ryegrass,  some  of  the  clovers,  and  to 

/'  potatoes  or  grain.    The  risk  of  damage  to  crops  and  lands  from  fires 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,   CALIFORNIA.  27 

caused  by  steam  harvesters  is,  however,  of  some  importance  in  grain 
])roduction.  Harvesting  is  also  sometimes  interfered  with  by  the  wet 
condition  of  the  hinds,  resulting  from  high  water  and  imi)erfect  levee 
or  drainage  systems. 

In  the  older  reclaimed  districts  and  in  those  not  devoted  to  special 
crops  this  soil  is  especially  adajited  to  the  growing  of  hay  and  forage 
crops  in  connection  with  dairying  and  stock  raising. 

Of  the  foregoing  crops  grain,  jwtatoes,  beans,  asparagus,  onions, 
and  other  vegetables  are  the  principal  products.  Dairying  is  also  an 
nnportant  interest.  Alfalfa  is  successfully  grown  upon  some  of  the 
earlier  reclaimed  and  better  drained  tracts.  In  newly  reclaimed 
districts  crops  are  sometimes  uncertain  for  the  first  one  or  two  seasons, 
owing  to  imperfections  and  delay  in  establishing  proper  drainage 
conditions.  Considerable  risk  and  expense  always  attend  the  prac- 
tice of  agriculture  upon  this  soil  type,  but,  with  the  exceptions  noted, 
the  yields  and  profits  during  favorable  seasons  are  usually  so  great 
as  to  offset  occasional  losses. 

SPECIAL  SOIL  PROBLEMS. 

The  occurrence  of  a  hardpan  formation  witliin  the  limit  of  the  root 
zone  of  crops  is  of  great  importance  in  its  bearing  upon  percolation, 
drainage,  the  conservation  of  soil  moisture,  and  direct  effect  upon 
plant  growth.  Not  only  is  the  root  zone  of  crops  greatly  limited  by 
the  occurrence  of  impenetrable  hardpan  strata  lying  near  the  soil 
surface,  but  cultivation  is  frequently  interrupted,  the  movement  of 
soil  water  arrested,  drainage  retarded,  and  the  power  to  retain  and 
to  deliver  moisture  decreased.  Lands  in  w^liich  this  hardpan  occurs 
usually  become  dry  during  periods  of  drought  or  dry  seasons,  and  if 
irrigated,  frequently  become  Avaterlogged,  crops  thus  suffering  from 
the  extremes  of  moisture  condition. 

In  the  Stockton  area  hardpan  is  of  frequent  or  of  general  occur- 
rence in  a  few  of  the  soil  types.  It  is,  however,  subject  to  great  varia- 
tion in  structure  and  in  its  effects  uj)on  agriculture.  The  most 
pronounced  hardpan  is  found  in  the  San  Joaquin  loam  and  the  San 
Joaquin  sandy  loam,  lying  along  the  eastern  margin  of  the  sheet.  It 
is  generally  of  light-red  color,  fine  texture,  save  for  an  occasional 
inclusion  of  gravel,  and  dense  structure,  impenetrable  to  the  soil 
auger  or  to  the  roots  of  plants.  It  usually  occurs  at  a  depth  of  from 
but  a  few  inches  to  3  feet  and  is  frequently  exposed  at  the  surface 
by  slight  erosion.  It  does  not  soften  upon  application  of  water, 
and  when  exposed  to  the  air  weathers  very  slowly.  It  is  of  secondary 
formation,  resulting  from  physical  and  chemical  changes  that  take 
place  in  the  soil  and  cause  the  cementing  of  the  material  into  a  dense, 
impenetrable  mass.  The  red  color  is  produced  by  the  iron  salts 
present  in  the  soil,  and  this  mineral  is  doubtless  instrumental  in  the 
formation  of  the  hardpan. 


28  FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,    1905. 

Throughout  the  eastern-central  part  of  the  area  a  much  less  in- 
tractable and  therefore  less  injurious  hardpan  occurs.  It  is  found 
within  the  zone  of  ordinary  root  development  only  in  the  case  of 
some  of  the  lower  lying,  heavy  adobe  soils,  and  amounts  merely  to 
j^artial  cementation  of  the  underlying  heavy  loam  subsoil  by  lime 
carbonate.  A  thin  whit^  crust  of  true  lime  carbonate  hardpan  of 
quite  dense  structure  frequently  separates  the  soil  and  subsoil.  Both 
this  crust  and  the  Underlying  compact  and  partially  cemented  subsoil 
are  j^enetrated  by  the  soil  auger  and  j^robably  frequently  by  the 
roots  of  trees  and  field  plants.  It  lies  uniformly  at  a  lower  depth 
than  the  hardpan  first  described,  which  is  another  reason  why  it  is 
much  less  injurious  in  its  effects  upon  crops. 

The  white  hardpan  of  the  Fresno  fine  sandy  loam  occurring  in  the 
southern  and  eastern  parts  of  the  area  is,  however,  of  a  more  dense 
and  firm  character  and  of  greater  importance  in  its  influence  upon 
growing  crops.  This  material  consists  of  a  firm  white  stratum, 
usually  only  a  few.jnches  in  thickness,  of  fine  texture,  and  ashy  con- 
sistency when  pulterized.  It  softens  slowly  upon  application  of 
water.  Several  of  these  strata  may  occur  separated  by  the  uncon- 
solidated soil.  Much  of  the  fine  ashy  material  is  probably  of  vol- 
canic origin,  rich  in  alkali  salts,  and  consolidated  by  lime  and  alkali 
carbonates.  It  does  not  approach  the  surface  so  closely  as  to  inter- 
fere with  plowing  or  other  cultivation,  and  is  much  less  extensive, 
uniform,  and  continuous  than  the  red  hardpan  found  in  the  eastern 
part  of  the  area.  It  is  of  importance  mainly  as  being  the  seat  of 
much  of  the  injurious  alkali  salts  of  this  district  and  in  its  effect  of 
retarding  the  removal  of  such  salts  by  the  drainage  water. 

A^Hiile  no  areas  occur  in  the  Stockton  area  that  may  be  properly 
designated  as  ''  worn-out  "  lands,  the  productiveness  of  certain  soils 
of  the  valley  and  delta  has  been  decreased  by  continued  cropping  to 
grain  or  other  crops.  In  such  cases,  a  more  careful  system  of  culture, 
the  rotation  of  crops,  the  production  of  fat  stock  and  farm  animals, 
and  the  practice  of  a  more  diversified  system  of  farming  are  to  be 
recommended  where  consistent  with  location  and  with  climatic  and 
soil  conditions. 

The  improvement  of  the  areas  of  "  burned-out "  Peat  is  also  a 
matter  of  importance.  Careful  management  is  necessary  to  bring 
these  patches  to  their  former  state  of  productivity.  The  addition 
of  coarse  animal  and  vegetable  manures  and  the  culture  of  clovers, 
forage  crops,  and  the  practice  of  green  manuring  is  recommended. 

RECLAMATION    OF    SWAMP   LANDS. 

It  is  to  modern  engineering  skill  in  the  erection  of  levees  and  the 
drainage  of  the  delta  or  swamp  lands  covering  the  most  of  the 
western  portion  of  the  Stockton  area  that  this  extensive  district  owes 
its  agricultural  importance.     Lying  but  a  few  feet  above  low-tide 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA.  29 

level,  these  island  tracts,  as  previously  noted,  are  thickly  covered 
with  a  dense  <>rowth  of  the  round  tule  {Srirpits  hieiisfrf's).  This 
aquatic  reed,  dyin<y  down  each  year  and  again  annually  springing  up 
from  the  roots,  together  with  rank  acpiatic  grasses,  soon  forms  a  more 
or  less  completely  submerged  mat  of  partially  decouii)osed  vegeta- 
ble remains  which  readily  collects  alluvial  dei)osits  from  the  flooded 
streams  and  gives  rise  to  a  rich  soil,  mapped  as  Peat.  The  develop- 
ment of  this  st'ction  has  made  rapid  strides  during  the  past-  few  years, 
and  tile  reclamation  of  other  extensive  tracts  is  still  in  progress, 
Avhile  in  the  northwestern  margin  of  the  map  accompanying  this 
report  is  indicated  by  swamp  symbol  a  large  area  still  unreclaimed. 

Although  early  efforts  were  -.successful  in  bringing  under  cultiva- 
tion large  and  valuable  tracts  bordering  the  upper  courses  of  the 
streams,  upon  some  of  the  tracts  adjoining  the  lower  San  Joaquin 
River  reclanuition  works  of  early  construction  have  been  completely 
destroyed  and  the  land  has  returned  to  its  native  condition. 

Reclamation  of  these  lands  consists  essentiall}^  in  throwing  up 
levees  or  dikes  along  the  streams,  thus  protecting  the  lands  from 
inundation  at  every  recurring  flood  or  period  of  high  tide.  This  is 
followed  by  construction  of  drainage  ditches,  the  removal  of  the 
waters  from  the  soil  by  pumping  over  the  levees,  and  the  bringing 
of  the  land  under  cultivation  by  appropriate  means.  The  last-men- 
tioned stej)  will  l)e  touched  upon  under  "Agricultural  methods." 
In  the  construction  of  the  earlier  levees  the  spade,  wheelbarrow,  and 
scraper  were  largely  employed.  The  levees  were  built  close  to  the 
edge  of  the  streams,  with  narrow  crown  and  abruptly  sloping  walls. 
Settling  frequently  caused  the  levee  to  topple  over  or  the  loose  Peat 
soil  was  quickly  eroded  away  by  the  currents  during  heavy  floods. 

AVitli  the  introduction  of  the  steam  dredger  and  the  benefit  of  expe- 
rience, and  the  employment  of  engineering  skill,  levee  construction  has 
become  more  successful.  These  dredgers,  of  the  ''  clam-shell "  type, 
work  day  and  night  and  are  capable  of  removing  tons  of  sediment 
from  the  stream  l)ottoms  in  a  few  minutes,  placing  the  material  in 
proper  position  upon  the  levee.  Owing  to  the  soft,  spongy  nature  of 
the  deeper  peat  and  finer  alluvial  deposits,  the  newly  made  levee  soon 
settles  and  the  process  must  be  repeated  until  a  coiidition  of  stability 
is  reached.  When  the  mass  has  settled  sufficiently  to  have  reached 
the  firm  underlying  sands,  no  further  addition  is  usually  required  save 
for  an  occasional  leveling  up.  The  better  and  most  successful  levees 
are  now  built  at  some  distance  back  from  the  rivers,  the  distance 
var3nng  from  40  to  200  feet,  and  have  wide  bases  and  crowns  and 
moderately  sloping  faces.  In  the  American  Review  of  Reviews  for 
Septem])er.  11)04,  in  an  article  written  by  ]Mr.  A.  J.  "Wells,  the  average 
cost  of  leveeing  is  given  at  from  $15  to  $20  an  acre.  The  cost  is  com- 
monly assessed  pro  rata  upon  the  owners  of  the  lands  benefited,  organ- 
ized into  reclamation  districts. 


30  FIELD    OPERATIONS    OF    THE    BUREACT    OF    SOILS,   1905. 

In  draining  areas  inclosed,  the  water  is  pumped  over  the  levees 
from  artificial  drainage  channels  or  from  minor  natural  sloughs 
serving  that  purpose.  For  this  work  pumping  plants  are  employed, 
either  permanently  located  near  the  levee  or  installed  upon  barges 
and  towed  from  place  to  place.  The  small  plants  and  those  of 
medium  size  are  usually  permanent  and  are  o]3erated  by  gasoline  or 
by  steam  generated  with  crude-oil  fuel.  The  larger  plants  used  in 
the  first  freeing  of  the  tracts  of  the  flood  waters  frequently  consist  of 
batteries  of  powerful  centrifugal  pumps.  These  are  operated  by 
steam  and  are  sometimes  installed  upon  floating  barges,  which  are 
particularly  serviceable  from  the  ease  with  which  they  may  be  moved 
from  place  to  place. 

While  extensive  tracts  are  still  partially  or  wholly  unreclaimed, 
practically  all  the  lands  lying  within  the  Stockton  area  are  reclaim- 
able  and  will  doubtless  soon  be  rendered  capable  of  cultivation. 

WATER    SUPPLY    FOR    IRRIGATION. 

For  many  years  irrigation  in  the  vicinity  of  Stockton  was  generally 
considered  unnecessary.  With  the  introduction  of  fruits  and  other 
specialized  crops,  however,  the  artificial  application  of  water  often 
proved  very  beneficial.  The  building  up  of  the  dairying  industries, 
fostered  by  the  growing  of  alfalfa,  rendered  irrigation  a  necessity,  for 
although  in  the  growing  of  fruits  and  vegetables  much  may  be  done 
with  an  intermittent  or  limited  water  supply  supplemented  by  fre- 
quent cultivation,  the  growing  of  alfalfa  calls  for  a  more  extensive 
system,  cheap  and  abundant  supply,  and  thorough  and  regular  appli- 
cation. 

The  great  part  of  the  area  surveyed  still  remains  unirrigated,  but 
the  practice  is  becoming  more  common  with  the  developinent  of  inten- 
sive agriculture.  The  w^ater  used  for  irrigation  is  derived  partly  from 
the  streams  and  partly  from  a  subterranean  source.  In  the  southeast- 
ern part  of  the  area  a  considerable  acreage  is  covered  by  the  lower 
branches  of  an  extensive  system  of  canals  and  laterals,  the  water  being 
taken  from  Stanislaus  River.  Another  system  of  considerable  pro- 
portions, taking  water  from  the  Calaveras  River  near  Stockton, 
passes  through  the  north-central  part  of  the  area.  Most  of  the  water 
afforded  by  this  latter  system  is,  however,  applied  in  the  vicinity  of 
Lodi  and  Woodbridge,  which  are  some  distance  north  of  the  limits 
of  the  district  mai)pcd. 

Alfalfa  is  the  principal  crop  irrigated  under  these  systems  in  the 
Stockton  area.  While  the  water  supplied  by  them  is  sometimes  lim- 
ited in  amount,  there  is  in  general,  particularly  under  the  system 
taking  water  from  the  Stanislaus,  more  than  enough  for  the  area  cul- 
tivated, so  that  if  a  tendency  toAvard  the  reckless  and  too  lavish  use  of 
irrigating  waters  could  be  checked  the  area  irrigated  could  be  here 
greatly  extended. 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNTA.  31 

Irrigation  upon  the  delta  lands  lying  below  ordinary-  or  high-tide 
level  of  the  adjacent  streams  is  cheaply  and  easily  effected  by  tapping 
the  streams  through  head  gates  placed  in  the  levees.  Alfalfa,  vege- 
tables, and  the  special  crops  of  the  island  district  are  supplied  with 
water  in  this  manner,  for  although  the  water  table  lies  close  to  the 
surface  in  this  district,  capillary  movement  is  slow  and  the  surface 
soil  becomes  very  dry  during  the  protracted  dry  sunnner  season.  The 
character  of  the  stream  water  of  the  Stockton  area,  as  regards  fitness 
for  irrigation  purposes,  is  highly  satisfactory.  The  water  derived 
from  an  underground  source  is  raised  by  windmills  or  small  pumping 
plants  operated  by  electricity,  gasoline,  or  steam  generated  with 
crude-oil  fuel.  While  tracts  so  irrigated  are  small,  there  is  in  the 
aggregate  a  considerable  area  devoted  to  the  cultivation  of  alfalfa, 
vegetables,  and  fruit  irrigated  in  this  manner.  The  water  derived 
from  the  first  water-bearing  stratum  is  frequently  greatly  inferior 
in  purity  to  that  taken  from  the  streams.  That  from  the  second  or 
third  stratum,  tapped  by  the  most  of  these  plants,  is,  however,  rela- 
tively free  from  soluble  salts,  and  may  be  considered  safe  for  use  in 
irrigation. 

UNDERGROUND    AND    SEEPAGE   AVATERS. 

The  character  of  the  underground  water  is  of  interest  in  giving 
some  indication  of  the  quantity  and  character  of  the  soluble  mineral 
salts  in  the  subsoils,  such  salts  readily  making  their  appearance  in 
the  water  of  wells  or  springs. 

In  the  western  section  of  the  delta  part  of  the  area,  particularly 
in  the  vicinity  of  Holt  and  westward,  the  underground  water  fre- 
quently carries  in  solution  relatively  large  quantities  of  alkali  salts, 
indicating  their  presence  in  the  soils  to  some  depth.  Of  these  salts 
sodium  chloride,  or  common  table  salt,  usually  occurs  in  large  quanti- 
ties. In  certain  districts,  however,  the  more  nauseating  magnesium 
salts  predominate,  and  many  of  the  wells  carry  such  quantities  of 
these  salts  as  to  be  unfit  for  domestic  use.  The  salts  probably  origi- 
nate in  marine  deposits  of  a  much  earlier  period,  and  although 
occurring  in  some  quantity  in  the  aggregate,  owing  to  peculiar  soil 
conditions  need  occasion  no  alarm  as  long  as  the  normal  structure  of 
the  soil  is  not  disturbed. 

The  occurrence  of  seepage  water  in  an  irrigated  district  is  usually 
due  to  the  immoderate  use  of  water  in  irrigation,  or  to  the  loss  of 
water  by  leakage  or  seepage  through  the  soils  from  canals  and  reser- 
voirs, coupled  with  natural  conditions  of  deficient  drainage.  This 
usually  leads  to  a  condition  of  water-logged  soils  occurring  along  the 
lower  slopes,  the  formation  of  rank-smelling,  disease  and  insect  breed- 
ing pools,  and  unproductive  marshes. 

Although  profuse  irrigation  may  be  carried  on  for  several  years 
before  the  appearance  of  these  water-logged  areas  or  seepage  sinks, 


32  FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,   1905. 

under  conditions  favoring  their  appearance  the  tendency  is  always 
towaid  their  rapid  increase  in  number  and  extent.  While  such 
extreme  conditions  as  occur  in  many  heavily  irrigated  districts  are 
not  apparent  in  the  Stockton  area,  there  are  a  number  of  small 
spots  and  local  depressions  lying  in  the  southeastern  portion  of  the 
area  that  have  been  subject  to  considerable  injury  in  this  way. 

Unless  greater  economy  be  practiced  in  the  use  of  Avater  it  is 
feared  that  areas  of  seepage  lands,  at  present  not  extensive,  may 
rapidly  increase.  An  outlet  should  also  be  provided  for  these  local 
areas  of  naturally  deficient  drainage  by  construction  of  open  ditches, 
or  preferably  by  tile  drains,  of  sufficient  capacity  to  remove  the 
excess  soil  or  seepage  waters  from  water-logged  slopes  and  flooded 
sinks  and  convey  them  into  natural  or  artificial  channels  leading  to 
the  larger  streams. 

ALKALI    IN    SOILS. 

Alkali  salts  exist  in  injurious  quantities  in  only  a  relatively  small 
part  of  the  soils  of  the  Stockton  area  {see  colored  Plates  I  and  II). 
In  the  vicinity  of  Stockton  an  occasional  small  patch  sometimes 
appears.  This  condition  is  especially  noticeable  in  one  or  two  locali- 
ties along  the  Linden  road.  Areas  of  slight  concentration  also  occur 
immediately  northwest  of  Stockton  and  along  the  edge  of  the  swamp" 
lands.  The  main  alkali  areas  are  found  in  the  southern  and  south- 
eastern parts  of  the  area,  usually  in  areas  of  the  Fresno  fine  sandy 
loam  and  also  in  limited  areas  of  reclaimed  Peat  lying  a  short  dis- 
tance west  of  Rough-and-Reacly  Island. 

Excluding  the  deposits  in  the  peat,  where  the  alkali  salts  have  been 
derived  from  marine  sediments,  the  alkali  of  the  Stockton  area  is 
derived  from  the  eruptive  or  altered  rocks  of  the  Sierra  Nevada 
Mountains,  from  the  volcanic  ash  material  occurring  to  a  great  extent 
in  the  soils  of  the  central  part  of  the  San  Joaquin  Valley,  and 
from  the  hardpaii  subsoil  of  the  Fresno  fine  sandy  loam.  Although 
termed  *'  alkali  "  salts,  very  few  of  the  salts  common  in  the  Stockton 
area  are  true  alkalis;  that  is,  of  alkaline  reaction.  Sodium  chloride 
and  sodium  sulphate  are  of  common  occurrence.  The  truly  corro- 
sive and  much  more  highly  injurious  sodium  carbonate  also  usually 
appears  wherever  the  total  salt  content  is  high  enough  to  threaten 
crop  production.  In  considering  the  injurious  effects  of  alkali,  0.20 
per  cent  is  considered  as  the  minimum  limit  of  danger  for  ordinary 
irrigated  crops,  this  amount,  while  not  greatly  in  excess,  usually  de- 
creasing yields  of  crops  to  a  certain  extent,  and  causing  the  appear- 
ance of  frequent  barren  spots.  In  the  case  of  the  sodium  carbonate/ 
or  "  black  alkali,"  however,  0.05  per  cent  is  considered  the  minimum 
concentration  beyond  which  crops  begin  to  suffer. 

Tlie  relative  concentration  and  distribution  of  these  salts  in  the 
soils   and    subsoils   depend    upon   a   variety   of   circumstances,    but 


REPORT    OF  BUREAU  OF  SOILS  US   DEPT.  AGR.  1905. 


Plate  I 


S? 


_J 


<t3 


^t 


REPORT    OF  BUREAU  OF  SOILS  U.S.  DEPT.  AGR.  1905. 


Plate  II. 


21-SL o. 


SOIL    SURVEY    OF   THE    STOCKTON    AREA,   CALIFORNIA.  33 

largely  upon  the  soil  texture  and  structure,  the  position  of  the  under- 
ground water  table,  and  the  rapidity  and  direction  of  the  movements 
of  the  soil  water.  In  soils  of  loose,  open  texture  and  structure, 
under  influence  of  gravity,  movements  caused  by  the  application  of 
water  in  excess  of  saturation  by  rainfall  or  irrigation,  the  salts  are 
dissolved  and  carried  downward  and  outward.  In  soils  of  fine  tex- 
ture and  compact  structure  the  movement  is  less  rapid.  Under  the 
influence  of  evaporation  upward  capillary  movement  takes  place, 
supplying  moisture  from  the  subsoils  at  the  surface  as  removed  by 
evaporation.  Conditions  favoring  rapid  evaporation  and  long- 
continued  capillary  movement — as,  for  instance,  long  periods  of  hot, 
(b"y  weather.  comi)act,  uncultivated,  and  unshaded  soil  surfaces,  and 
a  water-logged  condition  of  the  subsoils,  i.  e.,  the  occurrence  of  the 
water  table  near  the  surface,  a  condition  frequently  caused  by  the 
use  of  immoderate  <]uantities  of  irrigating  waters  upon  higher 
levels — tend  toward  concentration  of  the  alkali  salts  at  or  near  the 
soil  surface.  On  the  other  hand,  cultivation  and  consequent  forma- 
tion of  a  soil  mulch,  the  checking  of  evaporation  and  cai)illary  move- 
ment, the  heavy  application  of  water  to  the  surface  by  rainfall  or 
irrigation,  together  w'ith  conditions  favoring  the  drainage  of  the  sub- 
soils, tend  toward  the  removal  of  these  salts  from  the  surface.  In 
the  Stockton  area  the  alkali  salts  are  usually  concentrated  upon  or 
near  the  surface.  Occasionally  the  greatest  concentration  is  found  in 
the  underlying  hardpan,  but  rare!}"  does  the  accumulation  of  the 
alkali  salts  in  injurious  amounts  extend  to  the  depth  of  G  feet. 

Several  methods  have  been  proposed  for  the  partial  or  complete 
reclamation  of  alkali  lands.  The  only  permanent  method,  however, 
consists  in  thorough  underdrainage,  together  with  an  occasional  flood- 
ing of  the  surface.  As  soon  as  the  soil  is  freed  from  excess  of  salts 
thorough  cultivation  should  be  entered  upon,  using  some  of  the  more 
alkali-resistant  crops,  which  can  be  cultivated  frequenth%  or  which 
shade  the  surface — such,  for  instance,  as  sorghum,  sugar  beets,  or 
alfalfa. 

In  the  case  of  the  alkali  areas  occurring  upon  the  Peat  lands,  flood- 
ing, followed,  as  soon  as  the  soil  will  permit,  by  cultivation  of  the 
surface,  should  prove  beneficial.  As  much  coarse  vegetable  matter 
as  possible  should  be  incorporated  in  these  ashy  areas,  and  the  grow- 
ing of  forage  crops  to  prevent  evaporation  through  shading  the  sur- 
face should  be  undertaken  as  soon  as  practicable  after  flooding.  In 
the  case  of  the  local  alkali  spots  occurring  in  the  heavy  soils  lying 
east  of  Stockton,  the  practice  of  the  Italian  vegetable  gardeners  in 
making  heavy  applications  of  coarse  stable  manures  is  frequently 
beneficial,  improving  the  soil  structure  and  checking  surface  evapora- 
tion and  consequent  concentration  of  the  alkali  salts. 


34  FIELD    OREEATIONS    OF    THE    BUREAU    OF    SOILS,   1905. 

AGRICULTURAL  METHODS. 

The  Stockton  area  presents  wide  variation  in  agricultural  practices, 
which  range  from  those  applicable  to  the  most  extensive  to  the  most 
intensive  systems  of  farming.  In  general,  the  methods  employed 
are  well  adapted  to  the  soils  and  conditions  of  the  area,  though  im- 
provement is  possible  in  the  methods  of  irrigation,  cultivation,  and 
the  care  of  crops  in  some  sections  of  the  area. 

Upon  the  larger  ranches  and  tracts  labor-saving  machinery  has 
attained  a  wide  degree  of  usefulness.  In  the  case  of  many  of  the 
smaller  tracts  devoted  to  market  gardening  and  truck  growing,  the 
most  of  the  labor  is  performed  by  hand  by  Italians,  Chinese,  and 
Japanese,  although  a  wider  use  of  light  machinery  and  garden  tools 
would  frequently  prove  more  economical  and  efficient. 

Plowing  upon  the  extensive  grain-producing  tracts  is  done  with 
the  gang  plow  in  common  use  throughout  this  section  of  the  State. 
Wliile  the  seed  bed  is  sometimes  carelessly  prepared,  this  field  opera- 
tion is  in  general  carried  on  with  greater  thoroughness  and  diligence 
than  in  many  other  extensive  grain-growing  sections.  Plowing, 
harrowing,  and  seeding  operations  take  place  during  the  winter 
months,  the  grain  being  sown  by  drilling  or  sometimes  by  broadcast- 
ing machines.  Combined  harvesters  are  in  general  use  all  over  the 
larger  tracts,  some  of  which  it  is  reported  can  harvest,  thrash,  and 
sack  the  grain  from  a  hundred  acres  in  a  day  at  a  cost  of  14  or  15  cents 
per  100  pounds.  In  the  low-lying  island  districts  devoted  to  grain 
culture  farming  operations  must  be  carried  on  with  due  regard  to  the 
moisture  and  drainage  conditions  of  the  spongy  Peat  soils.  Untimely 
rains  (n-  floods  occasionally  render  the  soil  too  wet  and  soft  to  allow 
preparation  of  the  land  or  harvesting  of  the  crop,  although  under 
recent  improved  conditions  of  the  levees  this  unfortunate  condition 
does  not  often  occur. 

Upon  newly  reclaimed  or  soft  tracts  work  horses  are  commonly  pro- 
vided with  peat  or  "  tule  "  shoes,  offering  increased  surface  resist- 
ance and  preventing  the  sinking  of  the  animal  into  the  spongy  land. 
Powerful  traction  erlgines,  built  in  the  form  of  an  immense  tricycle 
and  provided  with  auxiliary  rollers  or  traction  wheels  4  or  5  feet 
wide,  are  also  extensively  used  to  compact  the  soil.  One  of  these 
modern  machines  performs  the  work  of  many  horses  in  hauling  a 
series  of  gang  plow^s,  harrows,  and  grain  drills,  plow^ing,  harrowing, 
and  seeding  the  land  at  one  operation.  They  are  also  again  brought 
into  requisition  in  hauling  the  combined  harvester  during  the  har- 
vest season,  in  repairing  and  improving  the  public  roads,  and  in  haul- 
ing heavy  loads.  Modern  labor-saving  machinery  likewise  plays  an 
important  part  in  the  production  of  some  of  the  special  crops  grown 
in  large  tracts  in  the  island  district,  although  its  use  is  here  subject 
to  greater  natural  restrictions. 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA.  35 

Preliminary  clearing  of  the  Peat  lands  consists  in  cutting  or  roll- 
ing the  tiiles  flat,  after  which  they  are  burned.  Care  must,  however, 
be  exercised  not  to  ignite  the  deeper  soil,  which  from  its  highly 
organic  character  may  be  largely  consumed,  leaving  the  land  ashy, 
unproductive,  and  filled  with  deep  and  dangerous  pits. 

Rotation  of  crops  and  the  use  of  barnyard  manure  or  other  ferti- 
lizers are  not  practiced  to  any  great  extent  upon  these  extensively- 
farmed  tracts. 

Irrigation  as  applied  to  the  chief  irrigated  farm  crop,  alfalfa,  is 
usually  carried  on  by  the  small  rectangular  or  contour  check  system, 
which  is  Avell  adapted  to  the  soils  and  topograplw  of  the  country. 
Upon  the  lighter  soils  of  the  southeastern  portion  of  the  area,  liow- 
ever,  the  lavish  use  of  irrigating  waters  is  a  dangerous  practice,  and 
if  unchecked  must  result  in  flooding  the  lower  lands  and  local  depres- 
sions with  seepage  w^ater,  thus  rendering  them  unproductive. 

The  delta  lands  devoted  to  the  production  of  asparagus,  vegetables, 
and  other  special  crops  are  irrigated  by  subirrigation,  the  water 
being  simply  allowed  to  flow  through  laterals  fed  by  a  main  line 
tapping  the  levee.  While  such  a  system  may  prove  ruinous  in  soils 
heavih'  impregnated  with  alkali  salts  and  subject  to  rapid  capillary 
movement,  it  here  proves  a  safe,  cheap,  and  convenient  method  of 
ajjplying  water  to  the  land. 

Ui^on  the  small  tracts  of  the  islands  and  in  the  vicinity  of  Stockton, 
devoted  to  the  growing  of  vegetables  and  fruit,  the  ordinar}^  opera- 
tions of  plowing,  harrowing,  and  cultivation  and  care  of  the  crop  are 
usually  quite  thorough.  Some  of  this  labor  might,  however,  be 
efficiently  and  more  quickly  performed  by  the  use  of  labor-saving 
machinery.  Cultivation  of  the  orchards  and  vineyards  is  sometimes 
neglected,  the  growth  of  noxious  weeds,  particularly  the  common 
wild  mustard,  allowed  to  go  on  unchecked,  and  pruning  and  spraying 
operations  ovei'looked.  In  harvesting  and  marketing  the  truck,  fruit, 
and  other  special  crops  the  methods  in  vogue  are  frequentl}^  worthy 
of  study  and  imitation.  Barnyard  manure  in  large  quantities  is 
applied  to  the  smaller  vegetable  gardens,  which,  Avliile  not  always 
essential  to  increase  the  plant  food  in  the  soil,  improves  the  struc- 
ture of  the  heavy  soils  and  promotes  increased  yield.  This  practice 
is  too  frequently  neglected  in  the  West  and  might  profitablv  be 
extended  to  most  field  crops. 

The  benefits  of  frequent  and  thorough  cultivation  in  developing  a 
proper  condition  of  tilth  in  the  heavy  adobe  soils,  in  preventing 
evaporation  and  conserving  soil  moisture  for  the  production  of  plants, 
and  in  checking  the  accumulation  of  alkali  salts  through  evaporation 
at  the  surface  of  some  of  the  lighter  soils  of  the  southeastern  portion 
of  the  area,  are  of  especial  importance. 


36  FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,   1905. 

AGRICULTURAL  CONDITIONS. 

The  value  of  the  farming  lands  of  the  Stockton  area  is  increasing 
rapidly.  The  farms  of  the  older  settled  districts,  particularly  those 
of  the  northeastern  part  of  the  area,  present  a  neat  and  orderly 
appearance,  and  excellently  tilled  fields,  well-built  fences,  and  sub- 
stantial and  commodious  farm  buildings  bespeak  the  prosperous  and 
contented  condition  of  their  owners.  In  other  less  favored  parts  of 
the  area  an  occasional  vacant  or  abandoned  farm  dwelling  is  seen, 
indicating  that  the  land,  usually  devoted  entirely  to  dry-farmed  grain, 
is  rented  and  farmed  by  some  neighbor  or  nonresident,  the  buildings 
sometimes  being  used  merely  temporarily  by  the  hired  hands  during 
the  harvest  season.  In  the  recently  reclaimed  districts  of  the  islands 
and  in  man}^  of  the  smaller  tracts  of  recent  conversion  to  truck  farm- 
ing, dairying,  and  intensive  agriculture  the  buildings  are  frequently 
very  modest,  of  cheap  construction,  or  merely  temporary  afi'airs  of 
rough  boards,  characteristic  of  newly  settled  districts. 

There  is,  in  general,  upon  the  part  of  the  farming  classes,  a  desire 
to  improve  their  condition,  and  to  take  advantage  of  modern  con- 
veniences and  labor-saving  devices.  Much  of  the  area  is  covered  by 
rural  free  mail  delivery  routes  and  many  of  the  more  isolated  farm 
dwellings  are  connected  by  telephone. 

AA'liile  quite  extensive  districts  w^ithin  the  alkali  belts  bordering 
the  swamp  or  tule  lands  and  also  in  the  southeastern  part  of  the 
area  are  valuable  in  their  present  condition  only  for  grazing  pur- 
poses, the  area  of  worthless  lands  or  those  incapable  of  being  brought 
under  j)rofitable  cultivation  is  very  small. 

Upon  the  older  reclaimed '  portions  of  the  islands  farmed  by  the 
actual  owners,  good  farm  buildings  are  of  frequent  occurrence,  but 
much  of  this  district  is  as  yet  held  in  large  tracts  and  rented  for  a 
cash  consideration  of  from  $6  to  $15  an  acre  per  annum,  the  tenants, 
mainlj^  Italians,  Chinese,  and  Japanese,  often  occupying  poor  or 
squalid  quarters.  This  section  could,  if  divided  into  small  tracts, 
and  devoted  to  dairying  and  intensive  agriculture  and  farmed  by 
actual  owners,  be  rendered  capable  of  supporting  a  large  population. 
Many  of  the  large  grain-producing  tracts  of  the  valley  are  also 
rented  upon  a  cash  or  crop-percentage  basis.  Statistics  sho^v  less 
than  half  the  number  of  farms  of  San  Joaquin  County  to  be  operated 
by  the  actual  owners.  This  condition  is  not  in  keeping  with  the 
opportunities  offered  in  this  section  for  the  practice  of  diversified 
farming,  dairying,  and  stock  raising,  or  the  growing  of  special  crops 
in  small  tracts. 

In  certain  districts,  particularly  in  the  southeastern  part  of  the 
area,  grain  farming  is  being  supplanted  by  dairying  in  connection 
with  the  growing  of  alfalfa  and  other  farm  crops.     Notwithstanding 


SOIL    SURVEY    OF    THE    STOCKTON    AREA,    CALIFORNIA.  37 

the  great  number  of  small  tracts  devoted  to  dairying  and  to  vegetable 
and  fruit  production,  owing  to  the  existence  of  the  many  large  valley 
farms  and  extensive  island  tracts  the  average  size  farm  in  San 
Joaquin  County,  according  to  the  cejisus  of  1900,  is  88'2  acres.  This 
is  more  than  ten  times  as  great  as  the  average  size  farm  in  some  other 
of  the  irrigated  districts  of  the  West,  the  natural  advantages  of 
which  are  far  less  favorable  to  crop  production  in  many  respects  of 
soil  and  climate.  While  not  all  the  lands  of  the  Stockton  area,  if 
intensively  farmed  in  20  or  30  acre  tracts,  would  be  capable  of  sup- 
porting a  family,  many  of  them  would  do  so,  and  the  average  size 
farm  may  well  be  reduced  coincidently  w'ith  the  further  develop- 
ment of  agricultural  industries.  Many  of  the  Italian  vegetable  gar- 
deners, by  great  thrift  and  unremitting  labor,  succeed  in  supporting 
large  families  and  in  accumidating  a  small  competence  upon  only  a 
few  acres,  and.  in  general,  small  or  medium  sized  farms  devoted  to 
diversified  farming  with  dairying,  stock,  or  poultry  raising,  and  the 
growing  of  fruits  and  vegetables  upon  a  small  scale,  are  more  to  be 
recommended  to  intending  settlers,  especially  to  those  unacquainted 
with  all  the  peculiar  features  of  climatic  and  industrial  conditions 
of  the  country,  than  the  more  extensive  farming  of  larger  tracts. 

Upon  the  valley  farms  the  general  farming  operations  are  usually 
intelligently  performed  by  white  labor  at  prices  current  upon  the 
Pacific  coast.  Upon  the  extensive  rented  island  tracts  much  of  the 
labor  is  performed  by  Chinese  and  Japanese.  In  the  raising  of  fruit 
and  truck  crops  Chinese  and  Italian  labor  predominates.  During  the 
grain  and  fruit  harvest  season  much  extra  labor  is  required  and  is 
frequently  performed  by  nomadic  laborers  of  mixed  races  and  of  a 
less  reliable  class.  In  ordinary  teaming  and  in  the  use  of  farm  ma- 
chinery white  labor,  while  usually  somewhat  more  costly,  is  preferred. 
The  more  tedious  hard  labor  necessar}^  in  the  growing  of  truck  crops 
and  fruits  is  generally  performed  by  the  Latin  races  and  Asiatics. 

The  production  of  grain  is  still  the  most  generally  practiced  agri- 
cultural industry  of  the  Stockton  area.  Wheat  is  the  most  important 
grain  crop,  followed  in  magnitude  by  barley  and  rj'^e  in  the  order 
named.  The  great  part  of  the  valley  lands  and  extensive  areas  of 
the  older  reclaimed  island  tracts  are  devoted  to  this  industr^^  A 
relatively  constant  rainfall,  together  with  productive  soils,  renders 
this  section  probably  the  most  important  grain-producing  district 
and  shipping  center  of  the  San  Joaquin  Valley.  AATiile  the  wheat 
produced  is  of  fair  weight  and  quality,  it  is,  in  common  with  all  Cali- 
fornia wheats,  somewhat  deficient  in  gluten  content  and  consequently 
of  inferior  milling  qualities.  Experiments  conducted  by  State  and 
Federal  authorities  are  now  in  progress  by  which  it  is  hoped  to  pro- 
duce strains  of  wheat  of  satisfactory  milling  qualities. 


38  FIELD    OPEKATIONS    OF    THE    BUEEAU    OF    SOILS,   1905. 

The  other  principal  crops  of  the  valley  lands  consist  of  alfalfa, 
table  and  wine  grapes,  and  deciduous  fruits,  mainly  almonds,  peaches, 
apricots,  and  cherries.  Almonds  are  especially  productive  and  profit- 
able when  properly  cared  for  and  when  not  subject  to  injury  from  the 
frequent  spring  frosts,  the  planting  of  the  hardier  stock  being  advised 
in  all  cases.  Choice  early  table  grapes  are  usually  in  good  demand 
and  salable  at  prices  giving  large  profits.  The  acreage  of  the  vine- 
yards is,  however,  being  rapidly  extended,  and  with  the  greatly 
increased  product  the  returns  from  ordinary  or  late  table  grapes  or 
wine  grapes  leave  a  narrow  margin  of  profit,  and  this  industry  should 
be  carefully  studied  before  embarking  in  it  extensively.  The  main 
fruit  and  grape-producing  sections  lie  in  the  eastern  and  northern 
parts  of  the  area. 

Among  other  important  crops  of  the  delta  lands,  potatoes,  beans, 
onions,  asparagus,  and  other  truck  crops  are  produced  in  great  quan- 
tities. Potatoes,  beans,  and  asparagus  are  j^robably  the  chief  crops 
of  the  newly  reclaimed  lands,  potatoes  being  generally  planted  as 
the  first  crop.  The  yield  and  value  per  acre  in  San  Joaquin  County, 
according  to  the  United  States  census  of  1900,  is  as  follows:  Beans, 
35.5  bushels,  valued  at  $55.03;  potatoes,  124.1  bushels,  valued  at 
$62.05  and  onions,  402.2  bushels,  valued  at  $232.28.  The  growing  of 
chicory  upon  a  commercial  scale  is  an  industry  of  some  importance. 

Dairying  and  the  raising  of  dairy  cattle,  beef  cattle,  horses,  sheep, 
poultry,  and  mules  ar6  well  recognized  industries  and  capable  of  being 
greatly  extended.  A  limited  number  of  pedigreed  horses  and  dairy 
cattle  of  national  reputation  are  produced,  but  the  growing  of  forage 
crops  and  the  production  of  stock  upon  favorably  situated  valley  and 
island  lands  has  been  greatly  neglected. 

While  more  or  less  unsuccessful  attempts  are  sometimes  made  to 
produce  upon  certain  soils  crops  to  which  they  are  not  adapted,  the 
principle  of  the  special  adaptation  of  soils,  through  peculiar  chemical, 
textural,  or  structural  features,  to  special  crops  is  commonly  recog- 
nized. Alfalfa  is  produced  chiefly  upon  the  sandy  soils  of  the  south- 
eastern part  of  the  area,  which  is  covered  by  extensive  irrigation 
works.  The  Peat  lands  are  generally  poorly  adapted  to  alfalfa, 
owing  to  the  close  proximit}'^  to  the  surface  of  the  ground  water. 
Some  of  the  clovers  and  grasses,  such^asjtimothyj  rje^rasSj,  etc.,  how- 
ever, here  do  well.  The  Peat  and  Sacramento  clay  loam,  if  properly 
managed,  are  better  adapted  to  the  growing  of  vegetables,  potatoes, 
and  the  other  special  crops  produced  in  this  section. 

The  main  public  roads  are  generally  improved,  and  during  the  dry 
season  good  wagon  roads  cover  nearly  the  whole  area.  During  the 
rainy  season,  however,  poor  natural  drainage  conditions,  with  the 
extremely  adhesive  nature  of  the  heavy  adobe  soils,  often  render  the 
country  roads  traversing  bodies  of  these  soils  practically  impassable. 


SOIL   SURVEY    OF   THE    STOCKTON    AREA,   CALIFORNIA.  39 

A  few  of  the  main  thoroughfares  are  turnpiked,  and  it  is  upon  these 
few  main  highways  that  nearly  all  wagon  traffic  is  carried  on  during 
the  rainy  season.  Upon  the  delta  lands  public  highways  are  also 
sometimes  poor  or  inadequate,  but  their  deficiency  is  largely  met  by 
navigable  natural  streams  or  artificial  channels.  Private  roads 
usually  follow  the  levees. 

The  area  is  traversed  by  two  transcontinental  railways,  while 
branch  lines  lead  to  valley  and  adjacent  foothill  points.  In  addition, 
river  steamers  reach  nearly  all  the  river  landings  daily,  or  at  less 
frequent  intervals,  offering  a  cheap  and  convenient  means  of  ship- 
ment of  produce  to  markets,  and  bringing  provisions  and  other  neces- 
sary articles  from  town  to  the  door  of  the  farm  dwellings,  and  in 
many  cases  serving  as  the  only  means  of  communication  with  the 
outside  world.  Stockton  and  San  Francisco  are  reached  by  steam- 
boat, by  sailing  vessels,  or  huge  barges  in  tow  of  smaller  gasoline 
craft.  The  river  steamer  here  takes  the  place  of  the  railroad  in  per- 
forming freight  and  express  service,  and  at  much  cheaper  rates,  while 
in  doing  the  shopping  in  local  markets  and  in  hauling  farm  produce 
to  shipping  points  the  private  gasoline  launch  and  small  barge  often 
perform  the  work  of  the  ordinary  farm  vehicles. 

Much  of  the  fruit  and  other  produce  is  shipped  by  rail  direct  to 
eastern  markets.  Stockton,  the  county  seat  and  manufacturing  cen- 
ter, is  a  grain  and  farm  produce  shipping  point  of  some  magnitude, 
and  furnishes  a  local  market  for  much  of  the  vegetables,  truck,  and 
dairy  products.  Grain,  flour,  feedstuffs,  potatoes,  vegetables,  wines, 
and  other  farm  products  are  shipped  in  large  quantities  by  water  to 
San  Francisco,  much  eventually  finding  its  way  to  the  newly  opened 
and  developing  markets  of  the  Orient. 

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